I'm also curious how much (extra) travel the slip joint has for lengthening travel of the driveshaft. (Kinda makes you wonder if lifts are as easy as some poster make it out!)
Never heard of anyone "dropping out"...least wise, not from lifting.
I dropped out once, but I hadda get sideways into a tree, breaking the weld on the R side lower link & moving the axle back, to do it...