Brand loyalty lines get blurred every time guys start talking about diesel engines. Dodge doesn't make the Cummins, Ford doesn't build the Power Stroke, and GM had to team up with Isuzu to design the Duramax. The reality is that each one of those engines could wind up in a bunch of different vehicles. Who's to say what badge should be on the hood?
The only limits to slipping any of these engines under the hood of a different truck are your own skills. Seeing as how the Cummins B-Series engine is probably the most popular engine for swapping, we wanted to follow along and see just what it takes to pull something like this off. We knew Bryan McCully of Fabworx Off-Road had been planning a factory-appearing Cummins swap for his '96 GMC K3500. So, we thought we'd follow along.
Bryan McCully began his swap by removing everything from the front of his '96 GMC K3500 to make pulling the engines in and out easier. McCully's truck was originally powered by a 6.5L turbodiesel. The 6.5L made 114 hp and 243 lb-ft at the rear wheels on a Mustang chassis dyno. After pulling the engine, he sold it for $500 and never looked back. | 
Sitting side-by-side with the 6.5L, it's clear the second-generation Cummins inline six-cylinder (left) is bigger in every dimension. When shopping for a donor engine, McCully knew he'd be ahead on time and money if he had a complete donor 5.9L Cummins Dodge truck to pull the engine from. He found a '95 two-wheel-drive Ram that had been T-boned on the driver side. Plan on spending around $4,000 for a wrecked donor Dodge. When shopping for a donor, avoid anything that has been on fire or hit in the front end. | 
Using a manual transmission will make any Cummins engine swap easier. McCully's donor two-wheel-drive Dodge and recipient GMC 4x4 both had New Venture Gear NV4500 five-speed manual transmissions. |
As you can see the input shafts and clutch mechanism are completely different. Fortunately, these pieces proved to be interchangeable. | 
Jack Arrington was in charge of the transmission parts swap. Here, he removed the front input bearing retainer and input shaft from the Dodge NV4500. | 
He cleaned it, checked the gear and bearing for wear, and installed the Dodge shaft back in the GMC NV4500. All NV4500 transmissions require Castrol Syntorq LT (low temperature) 75W85. Don't try to cheap out and use anything else. |