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He put a Duramax in a ‘98 Sierra!

He put a Duramax in a ‘98 Sierra!

The Diesel Podcast Apr 08, 2026 55 min
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About this episode

Dakota walks through his Duramax swap into a 1998 Chevy K1500, choosing an LLY because he wanted something different than the usual 12-valve or LS swaps. He starts with a running donor truck, then details pulling the OBS drivetrain, avoiding a body lift, building custom mounts, and working through fitment and wiring challenges. The plan is reliability first, then targeting roughly 450–500 hp while staying mindful of transmission stress and inspection realities. He’s also documenting the build on YouTube and shares tips for anyone attempting an OBS Duramax conversion.

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Technical Too Afraid to Ask
Concept

Duramax swap

"I'm excited to chat with you today and learn about this LLY Duramax swap that you have. ... Tell us about the platform, the truck that you're doing, the swap on, and then why you chose a Duramax..."

A “Duramax swap” is when someone puts a Duramax diesel engine into a truck that didn’t originally have that engine. It’s more than just bolting it in—you also have to make the systems work together.

Car

LLY Duramax

"I'm excited to chat with you today and learn about this LLY Duramax swap that you have."

A “Duramax” is GM’s diesel engine. “LLY” is a particular version of that diesel, and people swap it into older trucks to get more modern diesel performance and parts support.

Concept

LS swaps

"Everybody does like their LS swaps, the common swap, or they build the 350 they have in them..."

“LS swaps” means putting an LS V8 engine into a different truck or car. People do it because the engines are common and there are lots of parts and guides to make it work.

Part

exhaust manifolds

"So I was getting exhaust manifolds tightened back up because they were leaking. The exhaust that somebody put on it was leaking."

The exhaust manifold is the part that gathers exhaust from the engine and sends it down the exhaust system. If it’s leaking, it can make the truck louder and can cause heat and fume issues.

Part

core support

"And then I noticed the core support was getting rotted. So I was like, man, I want to just pull that off and then order a new one."

The core support is the front metal structure that holds the radiator and other cooling parts. If it’s rotting, the cooling system can become misaligned and repairs get more complicated.

Part

radiator

"Well, so I drained the radiator, all that started pulling the core support off and I started looking at it."

The radiator holds engine coolant. If you’re taking the front support off, you usually have to drain the coolant first so you don’t spill it and so you can work safely.

Term

torque

"Have you felt the power of the torque, all that sort of stuff? Like, did that factor into doing it?"

Torque is the twisting force an engine produces. Diesel engines like the Duramax are often praised because they make high torque at lower RPMs, which translates to strong acceleration and effortless pulling.

Term

lifted truck

"And just to see this big three-quarter ton four-wheel drive like lifted truck just kind of had that acceleration."

A “lifted truck” has increased ride height versus stock, typically via suspension lift kits or larger tires. Lifting changes steering geometry and ride/handling, and it often goes along with off-road-focused setups.

Term

three-quarter ton

"And just to see this big three-quarter ton four-wheel drive like lifted truck just kind of had that acceleration."

“Three-quarter ton” is a truck class based on payload rating (commonly around 3/4-ton capacity). It usually corresponds to heavy-duty configurations like stronger axles, suspension, and towing capability.

Term

brakes were out

"He almost drove through my garage door because the brakes were out of it. So that was almost a little bit of a payment there."

“Brakes were out” means the truck wasn’t stopping properly or at all, which is a major safety issue. In a project context, it often happens when a vehicle is disassembled, has a failed brake component, or is missing/disabled hydraulic pressure.

Concept

body lift

"...a lot of people that I've seen that do these swaps, they do a body lift on the truck... I'm not a huge fan of body lifts... So I wanted to try to get it without doing any sort of lift on the body at all."

A body lift raises the cab/body higher off the frame to make more room underneath. Some people do it to fit bigger parts, but it can change driveline angles and ride feel, so the speaker is trying to avoid it.

Term

turbo

"I could take the turbo out through the, through the engine bay. I wouldn't have to pull the cab or anything like that."

A turbocharger (often shortened to “turbo”) uses exhaust energy to spin a turbine and force more air into the engine for better performance. The speaker’s point is that the turbo can be removed through the engine bay, which suggests good service access.

Term

downpipe

"I could probably change the downpipe on it right in the end, right in the truck as well. That's what I was going to ask you next was about the downpipe."

A downpipe is the exhaust pipe section that connects the turbo outlet to the rest of the exhaust system. It’s often a tight-fit item on turbo setups, so swap builders discuss whether it can be changed without removing major body components.

Term

engine out

"...we were getting the engine out because the garage that I have, it doesn't have a heater in it..."

“Engine out” means taking the engine out of the truck. It’s a big job, usually done when you’re doing major repairs or a swap.

Company

ARP

"...fresh gaskets all through the engine head studs obviously do like ARP or something just to get it..."

ARP makes stronger engine bolts and studs. People use them to help the engine stay sealed and handle more stress.

Term

gaskets

"...I do want to go in and put I want to put fresh gaskets all through the engine head studs..."

Gaskets are the seals between engine parts. Replacing them helps stop leaks and keeps the engine running correctly.

Term

warranty

"...the type of quality that's built behind it with an industry leading warranty that's really comprehensive."

Warranty coverage is a key differentiator when buying remanufactured engines. The speaker emphasizes that the engines come with an “industry leading” and comprehensive warranty, which reduces risk compared to buying an unknown used unit.

Term

OEM engine

"...sometimes the options that are out there it's just it's a basic OEM engine. You want a little bit more you don't want to have the same failure again..."

An OEM engine is the same type of engine the truck originally came with from the factory. The speaker is saying some people want more than just the exact same setup again.

Part

rods cranks, pistons

"They have tons of choices for rods cranks, pistons, valve train upgrades, tons of different things."

Rods and cranks are rotating engine components (connecting rods and crankshaft), while pistons are reciprocating components that compress the air/fuel mixture. The transcript lists these as part categories available for engine builds, implying a bottom-end refresh or performance build.

Term

lubricity

"DFC is a 6-in-1 formula, it cleans injectors, boosts C-tane, and it has four times the lubricity as their leading competitor."

Lubricity is how “slippery” the fuel is to protect the fuel system parts. If the fuel isn’t slippery enough, it can cause extra wear over time.

Company

HotshotSecret.com

"If you go to HotshotSecret.com, use code dieselpod20, it'll get you 20% off your order. We really appreciate the team and our friends over at HotshotSecret offering this discount code just for you guys."

They mention HotshotSecret.com as a place to buy diesel-related parts. They also share a discount code to save money on an order.

Term

firewall

"Me and my friend, we pulled the whole harness because on the 98, the harness is like on plugs right at the firewall. So like the inner harness and the outer harness are completely different,"

The firewall is the wall of metal between the engine area and the inside of the truck. Lots of wiring connections are placed near it, so it matters when you’re taking the harness apart.

Term

mark your wires

"Mark your wires because right now that's actually what I'm fighting with."

“Mark your wires” means label the wires before you unplug them. That way, when you put everything back together, you know exactly where each wire goes.

Term

motor mounts

"...how I built the motor mounts, you know, the custom CAD CAD cardboard aid and development. You're sitting on my makeshift welding table right now... like the motor sitting on on the mounts I made..."

Motor mounts are the parts that hold the engine in place inside the truck. When you swap an engine, you usually have to build or modify the mounts so everything lines up and fits safely.

Term

supercharge

"I have that 2010 I was talking about out back that I just put the flatbed off of the the Duramax on that truck and I want to supercharge that someday."

Supercharging adds forced air to an engine using a belt-driven compressor, letting it make more power than it would naturally. On a diesel build, it usually means additional supporting changes (fueling, intercooling, and tuning) to keep it reliable.

Term

EFI Live tune

"Cause when it fires up and you know, you're driving it and decide you want a little bit more power and I'm sure do an EFI live tune, you know, on it."

An EFI Live tune is a way to adjust how the engine computer runs the engine. After you add parts or change performance, a tune helps the truck run better and make the power you’re aiming for.

Term

aftermarket

"Now with the aftermarket and this kind of being your first diesel truck that you're, that you're going to be like going really heavy into like, what have you thought about the aftermarket side?"

Aftermarket means parts and upgrades that aren’t made by the truck’s original manufacturer. For diesel trucks, it’s where you go for performance and reliability improvements.

Company

Sinister Diesel

"I've been trying to stick more towards like, I think sinister diesel is more forward, but I'm not 100%."

Sinister Diesel is a company that makes aftermarket upgrades for diesel trucks. People mention them because they’re known for selling parts that are meant to work together.

Company

WC fab

"But like sinister diesel, uh, HSP, WC fab, all them guys, I could try to like watch more of their stuff... I know WC fab, they actually do."

WC fab is a company that builds custom parts for diesel truck projects. In this case, they’re known for kits that help swap a Duramax into older trucks.

Term

33s

"So my dad being a Dodge guy, my first truck was supposed to be a 98 Ram 1500. It was had the 5.2 and it was maroon single cab long box four wheel drive on 33s. It was a pretty sweet looking truck."

“33s” means the truck would have 33-inch tires. Bigger tires can make the truck look tougher and can change how it drives and how it uses fuel.

Term

four wheel drive

"So my dad being a Dodge guy, my first truck was supposed to be a 98 Ram 1500. It was had the 5.2 and it was maroon single cab long box four wheel drive on 33s. It was a pretty sweet looking truck."

Four-wheel drive means power goes to all four wheels. It helps the truck grip better in slippery or rough conditions.

Company

Kershaw

"Don't forget diesel fans, make sure and head on over to kershaw.kaiusa.com. Use code 20 TD eight FR 26 to get 20% off your order."

Kershaw is a knife company. The host is sharing a discount code for listeners.

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