Well I have a 89 YJ that I will be doing the same conversion on.

The 3 engines, I was looking at was the GM 6.2/6.5, Cummins 6AT, or the Cummins 4BT.

The Cummins 6AT is comparable size wise the Jeep straight 6. Runs smooth.

As others has said, the NV4500... Login to read more.