1998 tj or 1990 yj?
 

alright guys me and my father have done the impossible, which is taking a 1998 tj drivetrain and dropping it into a 1990 yj body frame.... it all mounts up perfectly, although had to modify the gas tank sheild so that the 1998 tj tank fits in perfectly.. also had to buy brand new gauges for the electrical portion of it. The thing runs and drives great. if you are going to attempt this project i must warn you it does get costly.. its roughly a 5000 dollar job. You must buy a painless wiring after market standalone computer. for a 1200 dollar price also had to buy 500 dollars in gm sensors for the new computer. the wiring is next nothing to do provided you find the wiring diagram in your haynes jeep manual. Also the alternator must be fitted with a proper backing for the battery charging system. I love my new jeep, although it is pretty complicating buying new parts for it :S but it has opened up a world of possibilities for my new toy. :) if you have any questions or think it cannot be done i will be more than happy enough to send pictures.