It's not every day you see these two nameplates on the same sheetmetal. When Buddy Clifton bought his '93 Jeep Wrangler YJ, he set out to build it with a purpose. Buddy is an explorer. He likes trails and scenery and enjoys the companionship of a few close friends to hit the trail with he and his wife. He quickly found out his Jeep's stock 4.0L gasoline engine was a bit anemic in the power arena, so a supercharger was bolted on to bring the power level up to par with the other vehicle modifications that had been added.
 The Jeep was already fitted...  The Jeep was already fitted with an Old Man Emu suspension kit that worked great with the 4.0L. It will need to be modified to hold up under the 745-pound Cummins engine. |  |  This is the heart of the Jeep,...  This is the heart of the Jeep, a 96 3.9L Cummins four-cylinder turbodiesel. The fit was tight on the passenger side, but once the installation was complete, it almost looks as if Jeep put it in from the factory. |
The problem was the inline-six gasser started to drink fuel like a bandit. The Jeep now averaged less than 9 mpg, and with the smallish gas tank, trips were becoming short and not too sweet. The fix for this problem was to install a more fuel-efficient engine that would still make some power. With a little research (did we mention that Clifton is an electrical engineer at the Jet Propulsion Lab in Pasadena, California?) he found a conversion to diesel power would suit his needs.
In a wrecking yard, a 3.9L Cummins turbodiesel inline four-cylinder was located. This little (compared to the 5.9L Cummins it shares its architecture with) engine was purchased along with the General Motors TH400 transmission still attached from a wrecked '96 Frito-Lay delivery truck.
The engine is mated to a GM TH400 three-speed automatic that was originally behind the Cummins engine. The transmission was fitted with an Advance Adapters output shaft that allowed it to mate up with the Jeep's original NP231 transfer case.