I had my IFS diff (86) rebuilt due to it leaking oil etc. Once i pulled it off i noticed that on the short side of the diff the flange had a lot of play.
The guy who rebuilt them told me that early model ifs diffs were just made like that with a few thousands of play (.08 to .15 thou) and he still tried to use the shims to correct it but it would just cause it to freeze up.
Any body ever hear something like this? I don't doubt the guy because Currie Enterprises contracts a ton of work to him...plus my boss has had about 50 to 60 rear ends done by him with absolutely no problems.