i know it's long, but please read it, i need help.
here's my problem. i have a '91 yj with the 4 cylinder and ax5 combo. at about 60,000 miles it had been grinding going into 2nd and 4th gear, upshifting and downshifting. then i lost 5th gear, due to the snap ring holding 5th gear on breaking. so, replaced the snap ring, all bearings and seals, and only 2 synchro's were bad(replaced only those 2, others looked really good). over $500 later, it still ground and i lost 5th gear again after 100 miles. we thought the shafts had been moving side to side(bearings were worn), but it turns out they had been sliding front to back, causing it to "pop" the snap ring apart. so, we shimmed it up, it still grinds, but still has 5th gear after almost 8000 miles. my question is, what would cause it to still grind with all new bearings and synchro's? could it be a shift fork or something? the guy who did it has been a gearhead forever, and is now also a retired john deere mech, so i have faith in him. i appreciate any help, thanks in advance.
Clay H.  

i forgot to say that if you time it just right it won't grind. if you shift into 2nd or 4th right as the engine falls to an idle then it doesn't grind, but you have to time it perfectly. i just thought that might help. thanks.  Clay H.  

Mine had the same symptoms.  One day when returning from lunch there were some hard shifts (mainly 4th to 5th) and I couldn't get it out of fifth. It's still stuck in fifth.  There is some problem with the 5th gear/overdrive on these transmissions.  I might add that I rebuilt the transmision (with the help of my uncle: a caterpillar Mechanic)at 175k mi.  Now it is in need again at 230k.  I have plans to tear it apart again and patch it in the next couple of weeks.