I believe the 8.5" rear did come in blazer's with a 5spd. I could see breaking an 8.5" if it was pushed enough.nickelsun692 said:S10s have come with 7.5", 7 5/8" and 8.5" rear ends. 8.5" should handle LS1 with or without an automatic. Rear end should never hook up enough to break an 8.5 from what I have read. I've also read but cannot confirm, that certain blazers have disc brake rearends. My suggestion is to find an an 8.5, ideally with posi, and salvage disc brakes from a blazer. (8.5 never came in blazers) I'm open to any corrections if somebody thinks otherwise.