Your back could very well be on the verge of coming out.
However, I don't think that is what happened in the front. It broke at the joint, and didn't actually pull apart correct?
If that is the case, was the joint a CV joint (rubber booted at the joint) or a U-joint (like a "plus" sign")?
If it was a CV joint, the angle of the lift just wore it out. Typical problem.
Either way if you can upgrade to a DC (Double-Cardan) drive shaft in the front (that is one where the transfercase has a Double-Cardan joint at the axle end has a u-joint) of proper length you'll be better off then any hokey spacer. If you go with my above recommendation then you'll also need to make sure you have u-joint yokes are both ends (transfercase and differential).
'04 WJ, 6" Clayton LA's, 242 SYE, 35" BFG MT KM2's, 4.56 gears, & D44a locked
'14 WK2 Limited - delivery pending:)