My opinion if you want drop in and simple, is to stay with a jeep factory set up. engine, trans, and tcase. 6cyl or 8cyl up to you, 3 or 4spd trans up to you, but my vote is a v8 with 4spd. being you have 73 axles your gearing may be 4.27 stock, I believe 3.73 was optional, so you have decent...