Typically the older years wont requier an SYE with 4.5" of lift. I have an 88' with 8" of lift and have NO vibes what so ever. So you should be good, but every Jeep is different ...
i have an 88 with about 6 inches of lift and i have no sye. i do have a tc drop kit though. i believe with older xj's you can get away with more lift and not run a sye kit. newer xj's i believe can barely get over 3 inches without one. best thing to do is put the lift on and see.
My 94 has about 4" of lift and does not have the t-case lowered. I'm still using the stock slip yoke and I have no vibrations. The best advice that I can give is to lift it, go for a drive and see what happens, then worry about it if it's not right.
sweet. I was thinking of going between 4.5 and 6.5...guess I'll have to see which doesn't need the sye (let's hope it doesn't) to save myself some money...for now. Thanks for the help.