I've read some things bout the 243 case and some say it could b a broken snap ring or bearing retainer ring that's letting one of the shafts move more than it should.
My 1997 z71 243 tranfer case wants to pop outta gear when I put it in reverse. It's not the transmission whatever it is it's in the tranfer case. Anybody dealt with this before. I've not took it apart yet that's my next step.