drive shaft question

I heard that a front drive shaft will work with a sye for a lifted 98 auto xj. I have lifted mine to 6" with little or no ill effects, maybe because i shimmed the rear end and installed a transfer case drop. I am also pushing 33" bfg all terrains. There is a nasty angle of the rear drive shaft and the transfer case though, but no vibes.I do like making projects on the jeep. My question is, should i get a sye and install a front drive shaft in the rear or just go with it (I have been for about a year now, but i love working on the rig). what are the front drive shaft lengths extended and collapsed. I am wondering if they will work on the rear as well with this much lift, I have read of people doing this with no poblems. Any info would be great, thanks guys.