TECHNICAL Q&A
PROBLEMS AND FIXES
I have a conversion project underway that will combine a 2015 Duramax 6.6L and Allison 6-speed with a 1955 Chevy 3800 stepside longbed pickup. I plan to use the truck to tow my enclosed classic car trailer here in Mississippi and the surrounding states. I am modifying the salvage 2015 Chevy 2500 chassis to accept the 1955 Chevy cab and box, but I need some dimensional information for this engine/transmission combination to make sure it’ll all fit into the early engine compartment. I also need to correctly position the radiator and intercooler, and possibly modify the transmission tunnel. I’m having a tough time locating this information. Can you help?
Lawrence Wilson Meridian, MS Lawrence, sounds like a fun project. In simple terms, if you have room for a GM big-block gas engine, the Duramax will fit into the available space and have adequate radiator clearance for the engine-driven fan. You may need to get creative when installing some of the ancillary components like locating the intercooler plumbing, batteries, airbox, electrical center and ECM/TCM computers, but the basic space requirements for the engine will closely follow that of a 454/502 gas engine in terms of width and length. Hood clearance is usually not a problem with the ’50s-era pickups. Our recommendation would be to carefully measure the engine compartment and transmission tunnel found in a 1988-98 Chevy/gmc full-size pickup. You can make cardboard templates to help you. Compare the dimensions of your 1955’s engine compartment to what you measure for the ’88-98 Chevy. The only transmission interference problem you might encounter is with the transmission tunnel where the bell of the Allison bellhousing transitions to the main transmission body. To get adequate clearance, we pushed the tunnel upward at the point of interference an inch or so in our 1989 Chevy using a hydraulic lift. No cutting was required. We contend that GM Powertrain used a 1988-98 C/K pickup when designing the engine packaging. Aside from needing to fabricate a custom set of motor mounts, the Duramax 6600 fits like it was designed for that engine compartment. Good luck, and let us know how the project unfolds.