How difficult is it to replace components in one of these transmissions? I am not a mechanic, but there are not too many bolts that I have not had out of the old Camaro. Put a new engine in, new exhaust and clutch this year. Dropped the trans many times, but have never opened it up. I think I have an issue with the 3/4 gears. They don't shift into easily, and downshifting to 3rd is a chore. Grinding.
Sounds like a synchro or too much play on the shaft that the 3/4 gears ride on. Does it go into 3 easier if you double clutch? Hard to say what it needs until you tear into it. If you have a service manual for the Camaro the steps to take should be in there. I've seen the inner workings of a Borg Warner T10 more than once but never tore into Muncie. I'd guess they are fairly similar. I'd bet you could handle it based on everything else you've done to the car.
Just take your time… you can find the manuals on-line. I broke a few of those when I was much younger and we got 'em fixed… you can do the same.
I've had a T5 apart (80s and newer mustang) and the only advice I have is be careful getting those shift forks out. I may (or may not) have had to buy new ones when I rebuilt mine.
