Is This The Ultimate Transmission for a Cummins?

The Dodge Ram is a full-size pickup truck line known for being used as a work vehicle and for towing, with a wide range of trims and powertrains. It often comes up in diesel-focused discussions because many Ram models are offered with diesel engines that emphasize torque and long-distance hauling. In a podcast context, it’s a common example when comparing major truck brands and how they’re used in real-world fleets.

The host is specifically calling out Ram/Dodge diesel trucks as having a well-known weak point: the transmission durability. In this episode’s context, they’re discussing how certain RFE transmissions can fail sooner than owners expect, especially when the truck is tuned or worked hard.

“68 RFE” is a specific Chrysler automatic transmission used behind Cummins diesel applications. The RFE naming refers to the transmission family, and enthusiasts often discuss it in terms of clutch-pack capacity, heat management, and how much power/towing load it can reliably handle.

Clutch packs are the stacked friction elements inside an automatic transmission that engage different gear ratios. Their size and capacity matter because they determine how much torque the transmission can transmit without slipping or overheating.

Tuning refers to changing the engine/transmission control calibration (often via a programmer or ECU software) to alter fueling, boost, shift behavior, and torque delivery. On diesel trucks, tuning can raise torque well beyond stock levels, which then stresses transmission components.

The host is describing a practical concept in drivetrain building: even with aftermarket upgrades, transmissions have hard limits set by internal hardware (like the case and clutch capacity) and by how much torque the tuning can command. That’s why “more upgrades” don’t always scale linearly with power or towing demands.

A billet flex plate is an aftermarket transmission-to-engine adapter plate made from billet aluminum/steel rather than stamped factory material. In high-power builds, it’s used to improve strength and durability when torque loads increase, especially during aggressive launches or heavy towing.

The Ford Flex is a mid-size crossover/people-hauler that was built to prioritize interior space and practicality over sporty driving. It’s the kind of vehicle that may be mentioned when talking about drivetrain components and how different parts are used across models. In a podcast, it can come up in technical conversations because its design and powertrain options make it a useful reference point.

An Allison conversion kit is an aftermarket package used to swap in an Allison automatic transmission (commonly used in heavy-duty applications) in place of a factory transmission. The idea is to improve durability and drivability for high-power diesel builds and heavy towing.

ATS is referenced as the company providing an Allison conversion kit. In this context, it’s a vendor offering the parts and support needed to perform a transmission swap for diesel truck builds.

“700 horsepower range” is used here as a practical threshold where the 68 RFE’s durability becomes questionable. The host’s point is that even if some builds survive, it may not be a reliable long-term solution for towing and daily use at that power level.

An “Allison swap” means replacing a truck’s original transmission with an Allison automatic transmission (commonly from GM’s Allison line). The big challenge isn’t just bolting in the gearbox—it’s integrating the transmission control and electronics so it communicates correctly with the truck’s engine and vehicle systems.

In a transmission swap, the “electronic side” refers to the control electronics and integration work—wiring, modules, and signals that let the transmission communicate with the truck’s systems. This is often the hardest part because the swap must behave correctly under different driving conditions and engine states.

“Integrate it with the truck” means making the swapped transmission function correctly with the vehicle’s engine control, sensors, and transmission control logic. For modern trucks, that integration is typically required for proper shifting, throttle/torque management, and fault-free operation.

“SETAC off out third row” is unclear in the transcript and may be a mis-transcription of a specific equipment/option or a vehicle configuration related to the truck’s setup. Because the phrase isn’t standard automotive terminology as written, it’s not possible to confidently define it from this excerpt alone.

An Allison controller is the transmission control unit used with Allison automatic transmissions. In this segment, the speaker says the transmission control is handled by the latest T87 ECM/TCM “from for the Allison controller,” meaning the kit’s electronics integrate with the transmission’s control strategy.

ECM (Engine Control Module) and TCM (Transmission Control Module) are vehicle computers that manage engine and transmission behavior. The speaker is describing that the kit’s transmission control is handled by the latest T87 ECM/TCM, which helps explain why different truck years can still drive similarly.

This is about transmission packaging: the Allison transmission’s longer physical length changes how the driveshafts must be arranged. The speaker says this is why you end up with a shorter rear driveshaft and sometimes need a front driveshaft spacer for correct fitment.

The rear driveshaft transfers torque from the transmission to the rear differential. In a transmission swap/kit context, changing transmission length can require a shorter rear driveshaft to maintain correct alignment and driveline geometry.

A driveshaft spacer is a hardware piece used to adjust the spacing/position of driveline components. The speaker says the kit includes a spacer for the front driveshaft, but they personally didn’t use it because they had the front driveshaft done during the rear driveshaft work.

The 48RE is a specific heavy-duty automatic transmission used in some Cummins-equipped trucks. It’s commonly swapped out for other transmissions because people want different control features and better towing behavior.

A transmission cooler is a heat exchanger that helps keep automatic-transmission fluid temperatures under control. When swapping transmissions, the cooler plumbing often needs to be integrated so the new transmission gets proper cooling.

The torque converter cooler is part of the cooling system that targets heat from the torque converter circuit. The speaker says the Allison kit integrates into the factory torque converter cooler on the engine/block side.

A heat exchanger transfers heat from one fluid to another (or to air) so temperatures stay in a safe range. In transmission cooling, it’s the component that actually performs the heat transfer.

Fleece Performance is an aftermarket brand known for transmission cooling and related diesel truck parts. Here, the speaker says they used Fleece coolers and a line kit for an Allison conversion.

The Allison 1000 is a specific Allison Transmission model line designed for heavy-duty torque and towing use. The speaker is evaluating it as a daily-driver transmission after converting from a 48RE.

A tap shifter is a manual-style shifting interface (often paddle or lever “tap” controls) that lets the driver command gear changes. The speaker contrasts it with what they consider lacking control features on the 48RE.

Miles to the gallon (MPG) is a fuel-economy measure: how far the truck can travel per unit of fuel. The speaker uses it to compare the fuel economy they get after an Allison conversion versus what they saw with the 48RE.

Gear ratios describe how many times the transmission output turns for each turn of the engine. Different ratios let the truck keep the engine in a useful RPM band for towing, acceleration, or cruising.

RPM range is the band of engine speeds where the engine produces the most useful power and torque. A transmission’s shift strategy tries to keep the engine operating in that band instead of lugging or overspinning it.

Bogging down is when the engine loses momentum and RPM drops too far under load, reducing power delivery. In a diesel truck, it often happens when the transmission isn’t holding the right gear to keep RPM up.

“Locked up” refers to a torque converter clutch locking the converter so the engine and transmission rotate more directly. Lockup improves efficiency and reduces slippage, but if it happens at the wrong time it can make the truck feel less flexible.

Gear spread is the overall spacing between the transmission’s usable gear ratios. A wider or better-matched gear spread helps keep the engine in its effective RPM band across different speeds and loads.

The valve body is the hydraulic control center inside an automatic transmission. It routes transmission fluid to the clutches and bands that create each gear, so it directly affects shift feel and timing.

“LML valve bodies” refers to valve bodies associated with the LML Duramax-era application used in certain GM diesels. The host is saying later LML-spec valve bodies are used on newer trucks, implying different internal control/hydraulic behavior.

A “matched pair” means two components are designed to work together with compatible calibration and hardware. Here, the valve body and converter are described as needing to be paired from the same application to behave correctly.

The bell housing is the transmission’s housing that bolts to the engine and provides the interface where the torque converter/flywheel connects to the transmission. If it’s broken, the transmission can’t be mounted correctly, so replacing the bell housing is often part of getting the drivetrain back together.

The output housing is the part of the transmission that contains the output shaft and routes power out to the drivetrain. When swapping transmissions, matching the output housing (or replacing it) helps ensure the output shaft alignment and sealing are correct.

Allison is a well-known heavy-duty automatic transmission brand used in many diesel trucks. A “six-speed Allison” refers to an Allison automatic with six forward gears, valued for durability and the ability to handle high torque at towing and power levels.

A “core transmission” is a used transmission unit you buy as a base for rebuilding or reusing parts. People often source cores from junkyards or take-offs, then refresh the internals or combine components to build a working setup.

“Vowel body” appears to be a transcription error for a transmission valve body, which is the hydraulic control unit inside an automatic transmission. The valve body directs fluid to different clutches/bands to create gear changes, so swapping the correct one is important for proper shifting.

Drive shafts transfer rotational power from the transmission to the axles. When swapping transmissions between truck generations or configurations, the driveshaft lengths and/or front spacer setup may need to change to keep the drivetrain aligned and avoid vibration.

Cooler lines are the hoses/lines that route transmission fluid to and from a cooler. Keeping transmission fluid temperatures under control helps the transmission live longer and shift more consistently, especially when towing or making more power.

A “driveline change” means modifications to the components that transfer power from the transmission to the wheels—like driveshafts and related mounting/alignment. The host is saying the Allison swap is close enough in size/fit that you may not need to change much of that hardware.

“Sixth gear” is the top gear in a six-speed automatic, and the host is describing shift behavior—how the transmission locks into higher gear at certain speeds. The point is that the compared transmission’s shift strategy may leave the driver “never where you want them.”

“Lock up” refers to a torque-converter clutch locking the converter so the engine and transmission input rotate together more directly. This usually improves efficiency and reduces slippage, and it can change how smooth or responsive the truck feels at certain speeds.

“Duramax” is GM’s diesel engine family (commonly associated with Chevrolet/GMC heavy-duty trucks). The host is saying that in Duramax platforms, people have used Allison transmissions for a long time, especially for high-horsepower builds.

“Duramax” is GM’s diesel engine family (most often paired with Allison automatics in heavy-duty trucks). Here, the host is comparing how much work the Duramax setup needs versus running a high-power engine in front of an Allison.

In an automatic transmission, planetary gearsets use “planet” gears that work with sun and ring gears to create different gear ratios. “P2 planet” is a specific planet gear location/part within the Allison’s gearset that can be upgraded to stronger billet components for higher loads.

“Conversion kits” are aftermarket packages used to adapt an engine/transmission/controls combination into a different truck than it originally came from. The segment notes that kit design and the year of the donor truck can change what parts (like shafts) are required.

A transfer case splits power from the transmission to the front and rear axles in 4WD vehicles. The segment mentions building a transfer-case setup around a specific spline count (23 spline), which affects what output shaft is needed.

The “output shaft” is the transmission shaft that delivers torque to the transfer case/drivetrain. A “billet output shaft” is a stronger, machined version intended to survive higher torque in conversion builds.

“Spline” refers to the ridged connection between shafts and mating components. “23 spline” describes the number of engagement ridges, which is critical for compatibility between the transmission output and the transfer case.

“Cummins” refers to Cummins diesel engines, often swapped into other trucks for strong torque and durability. In this segment, the host is discussing putting a Cummins into a truck and then wanting an Allison transmission to match it.

A “PSC controller” is an aftermarket transmission control module used to manage shift behavior in certain engine/transmission conversion setups. The host implies that some kits require sending the controller to the installer and that the setup can be frustrating or not fully integrated.

“Clanky shifting” describes harsh, noisy gear changes that can indicate poor calibration, missing sensor inputs, or incomplete integration between the engine and transmission control systems. The host attributes it to the conversion not having the inputs the transmission needs.

“CAN” (Controller Area Network) is the vehicle’s internal communication bus that lets modules talk to each other. A “CAN plus system” in this context refers to the truck’s factory network that aftermarket modules may need to “tap into” to integrate with the rest of the electronics.

“Plug and play” means the replacement part is designed to connect to the factory wiring and controls with minimal modification. In aftermarket diesel applications, it usually implies fewer integration steps and less risk of wiring mistakes compared with kits that require splicing into the vehicle network.

DFC Diesel is presented as a podcast sponsor and aftermarket remanufactured-engine supplier. The segment emphasizes that their engines are built to an ISO 9001:2015 quality standard and backed by an industry-focused warranty.

Powerstroke is Ford’s diesel-engine line, widely used in Super Duty trucks. In this segment it’s mentioned as part of DFC Diesel’s remanufactured-engine lineup for different diesel platforms.

Remanufactured engines are rebuilt using a combination of reconditioned original parts and new components to restore the engine to a specified standard. Compared with buying a brand-new engine, remanufacturing is often aimed at balancing cost with reliability and warranty coverage.

ISO 9001:2015 is a widely used international standard for quality-management systems. In an engine remanufacturing context, the claim is that the supplier’s processes are audited and controlled to meet consistent quality requirements.

“Tow/haul” refers to a calibration or configuration intended for towing-heavy use, typically prioritizing drivability and transmission/engine behavior under load. In this segment it’s used as one of the engine “series” options, implying different setups for different duty cycles.

“Speed of air series” appears to be a named engine lineup or configuration category from the sponsor, likely tied to airflow and performance tuning. The phrase suggests a focus on how the engine breathes (airflow) rather than a generic “street” or “tow” setup.

“Speed of air pistons” refers to a specific piston technology sold/used by DFC Diesel. The host claims it’s designed to improve efficiency and pay for itself by enabling better fuel economy and durability when added to an engine build.

Fuel economy is how efficiently an engine converts fuel into motion—typically measured as miles per gallon (or liters per 100 km). The host ties the piston tech to improved fuel economy as part of a broader set of claimed benefits.

Lead time is the time between ordering parts and receiving them. The host emphasizes that DFC Diesel has engines/parts with short lead times or stock availability, which matters for planning a build.

Valve train upgrades modify the components that open and close the engine’s valves (commonly including parts like camshafts, lifters, springs, and related hardware). The host lists them as options for customizing an engine build beyond a basic “series of engines.”

Lubricity is how well diesel fuel lubricates the fuel system components (like injectors and high-pressure pumps). Low-lubricity fuel can increase wear and contribute to costly repairs, which is why the host frames it as a key issue.

Hot Shot Secret is the brand behind the diesel additive discussed in this segment. The host credits the brand’s EDT product with improving lubricity and injector cleanliness to help prevent costly repairs.

“C-tane” is a branded reference to cetane-related performance in diesel fuel additives. Cetane is a measure of how readily diesel ignites; higher cetane generally helps with smoother combustion and can reduce issues tied to poor ignition quality.

Hot Shot’s EDT is the specific diesel additive product being promoted. The host claims it’s a “six in one” formula that cleans injectors, boosts C-tane, and increases lubricity versus a leading competitor.

Here, “converters” refers to the torque converter used in automatic transmissions. It uses fluid coupling to transfer engine torque to the transmission and helps the truck launch smoothly.

Automatic transmissions use clutch packs made from friction materials to connect rotating parts. The clutch material’s friction characteristics strongly affect shift feel, heat, and durability under load.

An “eight-speed” automatic transmission has eight forward gear ratios. More gears can keep the engine closer to its ideal operating range, which can improve drivability and how efficiently the truck makes power.

“68” is shorthand in this context for the older 6-speed automatic used behind Cummins/Dodge applications (commonly referenced as the 68RFE). It’s being used as the comparison point for the newer eight-speed.

ETS (as used here) refers to an aftermarket transmission kit that allows fitting a different transmission into a Cummins/Dodge application. The key point is that it’s designed to work across a wide model-year range.

Adapter plates are mounting interfaces used to mate a transmission to an engine. In swaps, fewer or simpler adapter plates generally means less fabrication and a more straightforward installation.

“Grinding in the block” means modifying the engine block to create clearance for the transmission or related components. Avoiding this is a big deal because it reduces irreversible changes and potential fitment issues.

A flex plate is the thin, ring-shaped plate that connects the torque converter to the engine’s crankshaft in many automatic setups. Upgrading flex plates during a swap can help ensure correct strength and starter/torque-converter alignment.

This refers to the idea that the swap uses existing wiring interfaces so the transmission control signals can be connected without extensive re-engineering. When it works “plug-and-play,” it reduces install time and the chance of integration problems.

An exhaust brake is a device that restricts exhaust flow to create engine braking. On diesel trucks, it helps slow the vehicle using the engine rather than relying only on the service brakes.

Remote start is a factory or aftermarket feature that lets you start the engine from outside the vehicle. In transmission swaps, the point is that the truck’s existing electronics still behave as if the original transmission is installed.

“68 RV” appears to be shorthand for a specific Dodge/Ram 6-speed automatic variant (likely the 68RFE). The host’s point is that, from the truck’s perspective, the electronics still think it’s running the original transmission.

“20 hours” is used to describe labor time for a conversion. The host’s argument is that a simpler kit reduces shop time and therefore reduces cost compared with a more complex transmission conversion.

R&R is shorthand for remove and reinstall, a common shop phrase for how much labor a job takes. In this context, the host is saying the Allison swap is only a little more work than a typical remove-and-reinstall job.

“Glazing” refers to a clutch friction surface becoming smooth and heat-affected after slipping. Once glazed, the clutch can’t grip as well, so it tends to slip again sooner, creating a feedback loop toward failure.

Line pressure is the hydraulic pressure the transmission uses to apply clutches and control shifting. Increasing line pressure can help reduce clutch slip under load, which can improve durability when the transmission is being pushed.

The transmission pump is the component that generates hydraulic pressure and flow for clutch apply and lubrication. If the pump is weak or failing, pressure can drop under load, which can cause clutch slip and accelerate wear.

“Clutch slip codes” are diagnostic trouble codes triggered when an automatic transmission’s clutches don’t lock up firmly enough. That slip usually shows up under load (like towing) when the transmission can’t maintain the hydraulic pressure/flow needed to hold the clutches engaged.

“Built 68” is shorthand for building a 68RFE-style transmission (a common factory automatic in some Cummins applications) with stronger internal parts. The idea is to increase torque capacity and durability so it can handle higher horsepower and towing loads without slipping or overheating.

A “48 swap” is a transmission swap to a 48RE transmission (or related 48-series setup) rather than staying with the original transmission. It’s often discussed as a cost-effective alternative when the goal is moderate power and the truck isn’t used for heavy towing.

A “tune truck” means the engine control module has been reprogrammed (a performance calibration) to change fueling and boost behavior. On diesel Cummins setups, tuning is often the main path to power before adding hardware like intakes, turbo upgrades, or fuel-system changes.

An “SMB intake” is an aftermarket intake system brand/model used to improve airflow on a diesel. Intake upgrades can complement tuning by helping the engine breathe better, though they’re typically not as impactful as major fuel or turbo changes.

“CP3” refers to the Cummins high-pressure fuel pump (often called the CP3 pump) used to pressurize diesel fuel for injection. Upgrading the CP3 is a common way to support higher power levels because it can deliver more consistent high-pressure fuel under load.

“Compound turbos” means using more than one turbocharger in combination (commonly a high-pressure and low-pressure turbo) to improve boost response and airflow across a wider RPM range. On high-power diesel builds, compound setups can help manage exhaust energy and reduce turbo lag compared with a single turbo.