The Perfect Swap: LML Duramax-Swapped 1986 GMC

The nostalgia of the older body style Chevrolet and GMC trucks are somewhat astronomical. When people get wind of a clean “square body” it sparks massive interest. Most of these trucks came outfitted with a combination of engine and transmissions but what this truck ended up with was a dream for most.

We made a trip to Marshfield, Missouri, for a separate project we are working on and caught wind of Perkins Diesel being local. You may have heard of or seen the Perkins crew at major Lucas Oil Pro Pulling League events over the years as they have multiple trucks that can go the distance. Not only do they play hard, they work hard too.

Keeping the older GMC badges on the truck keeps the nostalgic theme.

After stopping in and speaking to Chad Perkins about their latest project, we had to see it to believe it. “We have a few of our trucks here, but you need to see our 1986 GMC,” said Perkins. “If you like these trucks, you’re definitely going to enjoy this.” Little did we know, we were in for a treat after catching glimpse of this dime.

We’re being told that this truck will be used to pull the pulling trucks to events as well as using it in truck shows.

As the shop door raised, we saw one of the best looking trucks in the country, but had no idea how much time and effort was invested in this project to get it where it is today. A cherry-red 1986 GMC truck that was powered by a 6.6-liter LML Duramax backed by an Allison transmission.

Leaving some room, this Duramax engine was a perfect fit for the engine bay.

After our initial walk around, we noticed that every detail had been covered by the Perkins Diesel crew. “The outside is great and all, but the really the best part of the whole build is inside,” Perkins said. After opening the door to the cab, we notice a complete late model dash inside. The truck has nearly every function a new GMC would come with.

This unbelievable transformation took countless hours of work.

One of the technicians we spoke with about the build was Andrew Tarter. “I was a little skeptical about this build and thinking what it would entail to complete it,” Tarter said. “But after further review, we tackled it anyway. The truck has come a long way because it was definitely not in this condition when we received it.”

The Beginning Of An Art Piece

The truck started out to be a clean piece, but it still needed a lot of work. Although it came with a clean plate to start, it was still going to take some time to get it where they wanted.

“About a year ago, this 1986 showed up at our shop with no engine, bed, or a hood,” Tarter said. “Being a Cummins nut, my first thought was this is going to be an awesome Cummins swap.”

Little did he know, Perkins had different plans. After using the donor engine out of a pulling truck, that was later swapped to a Cummins powerplant, they had their powerhouse for the GMC. “After ordering parts, customizing parts to work, and talking with a few people about the swap, we had over 300 hours of labor invested,” explained Tarter.

If this isn't one of the best transformations you've ever seen, we would like to see what you think looks better. Although it took 300 or more hours of labor, this truck turned out just right.

Arriving with no engine, it gave the team at Perkins plenty of space to make room for the new and improved engine. “The truck is fully functional just like a 2014 model,” Tarter continued. “Unlike before, the truck now offers useful accessories it didn’t before. The headlights stay on until they time out, just like the late model trucks do.”

Not knocking the original powerplants that came in these trucks, but we think we can all agree that they should have come this nice.

Out With The Old, In With The New

Previously swapping over to a more desired engine, they also added a few other exterior goodies that give the truck more of a wow-factor. That includes wheels, tires, five-inch exhaust, traction bars, and aftermarket head and tail lights.

Being a late model engine, they opted to utilize the new age tuning software from EZ-Lynk to get the truck even more horsepower and torque. Using the EZ-Lynk box, they have the truck custom tuned with PPEI software.

Featuring a set of Gladiator tires and Fuel Off-Road wheels, this GMC is ready for any terrain.

Although this wasn’t intended to be a show truck, it’s perfectly capable of it. The underside of this GMC was flawless.

The crew at Perkins Diesel tells us that this project couldn’t have been done without the companies that provided parts that include ATS Diesel, Air Dog Fuel Systems, ARP, EZ LYNK, Fleece Performance, MBRP Exhaust, PPEI, and Wehrli Custom Fab.

To you Ford owners, it’s okay to try something. If you can’t make it home, you’ve got some help readily available.

We’re extremely thankful we were offered the opportunity to see this gem and look forward to the future of the truck. For more information on the Perkins Diesel Shop check out their website. What’re your thoughts on this build? Let us know in the comments below.

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About the author

Artie Maupin

Artie Maupin is from Southeast Missouri and has an extreme passion for anything diesel. He loves drag racing of all kinds as well as sled pulling competitions.
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