I just finished up doing this yesterday. The top bolt is 18mm, a box end wrench fits nicely in the hole in the frame and then you can hit it from the other side. You do not need to take off any control arms! I read a bunch of posts on here that said you need to, but don't. You will need to remove the steering linkage, specifically the the crosslink for the tie rods. When you get the diff loose, take out the oil cooler on the driver's side of the engine. With that out, I was able to rotate the diff right out. Chevy has a kit (GM Part # 26033623) that has new thrust washers that you will probably want to pick up. It replaces 7, 20, and 24 in the above drawing. Also, GM # 14039577 is the seal for the passenger side driveaxle tube, #3 above. Those were the only things I replaced and it is working great. Let me know if you need any help. This wasn't as bad of a job as I thought it would be, just a little time consuming!
'96 S10 Blazer, V6, 4x4, Stock