I thought I'd need one when I did my 70 regear because I was not able to budge it once I pulled the carrier bearing caps. Turns out Ijust needed a longer prybar. I used a 3' prybar and a BFH to help coax it out. I thought I'd need a spreader to get it back in with the proper amount of carrier preload shims, but I was able to coax it back in again with a plastic faced hammer, when it was in far enough, I put the bearing caps on and tightened the bolts to suck it in the rest of the way. Worked ou, no prob, and I had to put it in and remove it 3 times due to unnacceptable gear patterns.
Now wait until you have to pull the carrier bearings! /forums/images/graemlins/eek.gif