I purchased my YJ, Used, from a guy that had in a back yard. It did not have a front differential, but I found one in a Junk Yard. The engine was on the jeep, but it was missing the head. Also, it had a manual transmission. I have installed an automatic one and an NP242 Transfer out a Grand Cherokee.
I have installed a Pro Comp Coil conversion on my Jeep, but I did not get the diff angle (Recommended on the instructions) before installing it.