Morgan Evans Swaps Duramax Diesel Into 1982 GMC

A 1982 GMC C3500 High Sierra dually received a Duramax diesel powertrain conversion in five days ahead of its SEMA Show debut.

Updated on Nov. 3, 2026 in Trucks

Morgan Evans Swaps Duramax Diesel Into 1982 GMC

Morgan Evans completed a Duramax diesel powertrain swap in a 1982 GMC C3500 High Sierra dually in five days, with the build finished in one week from Monday to Friday. The truck is set to debut at the SEMA Show in Las Vegas.

Why it matters

The conversion shows how a four-decade-old regular-cab square-body truck can be re-engineered with modern diesel and drivetrain components. It also highlights the growing trend of classic truck builds that pair vintage bodies with contemporary powertrains.

The rebuilt truck pairs a 6.6-liter Duramax LB7 diesel with a ZF S6-650 six-speed manual, replacing a 454-cubic-inch big-block and SM465 four-speed. Output figures and fuel economy for the finished build were not disclosed.

The players

Morgan Evans

Morgan Evans is the builder who completed the Duramax diesel powertrain swap on the 1982 GMC C3500 in five days.

The details

The exhaust was cut away with a Sawzall, and the core support was replaced with a new unit incorporating cooling and intercooling. The brake system was converted to hydroboost, the clutch to hydraulic, and the fuel system was adapted for diesel use.

Monday to Friday, week of SEMA Show 2026: Five-day Duramax swap build completed.
November 2026: Truck debuts at the SEMA Show in Las Vegas.

Roadmap

Classic square-body GM trucks have become a common platform for Duramax LB7 swaps, a practice that has grown alongside demand for diesel torque in restomods. This build follows that pattern by pairing a 1980s regular-cab body with a modern six-speed manual and hydroboost braking.

Owners considering a similar swap face a five-day conversion timeline only under expert hands, with added costs for hydroboost, hydraulic clutch, and fuel-system modifications. The approach keeps a vintage square-body usable with modern diesel torque and a six-speed manual.

The takeaway

Converting an older truck to diesel power involves coordinated changes to cooling, braking, clutch, and fuel systems, not just an engine replacement. Anyone planning a similar build should budget for those supporting modifications from the start.