If you decide to go with the 4.0 you will need to replace not only the engine but the transmission, wiring harness, and the list goes on. I think you might be able to reuse your gas tank and fuel pump because you started out with a fuel injected engine. I did a 4.0 swap in my 89YJ that had the 4.2 carbureted engine and it wasn't that difficult. I just found myself a $600.00 wrecked XJ and pretty much used everything from it (except for the fuel tank and sending unit that I found at a local junk yard). If you do decide to do the swap you will be really happy with extra HP gain with the 4.0. I think youíre still an OBDI with the 1995 or earlier? Iím sure someone will correct me if itís not. Try this website for some info also. http://www.cjoffroad.com/forums/topic.asp?TOPIC_ID=6408&SearchTerms=The,big,secret,is,out,-,wiring,OBDI

Good luck

89 YJ, 3.5" Black Diamond Lift, 33" tires, 8000lb Warn, 4.0 91 XY engine swap.