Mine wont stay in gear while driving. If you hold the shifter it is fine but when you let go it pops out of gear. How much does it normally cost for a rebuild? I think it is the m21.

Take the side cover off & check the springs and levers that are attached to the side cover that might be your problem, also maybe a shifter adjustment.

the first thing i would check would be shifter adjustment....

i got a muncie rebuild video a few years back. what a help! made my rebuild a snap. you can get a muncie rebuild kit and gaskets for cheap! just as long as you arnt buying new gears, case, midplate, and main shaft (pretty much all the hard parts) you can rebuild em for cheap.

this is your one stop muncie rebuild parts guy! great to deal with.

http://www.kajunjon.com/

link to the video

http://www.5speeds.com/video.html

hope this helps. i had a blast building my muncie.

The Feb issue of Chevy Punch has a GREAT highly detailed muncie rebuild.

If you've already checked the easy stuff like the shifter adjustment and side cover springs, then your trans needs some help. There are a couple of other cheap and fairly easy things to fix that you can also check.

If the trans is only jumping out of 4th gear, you can check for a worn pilot bushing in the end of the crankshaft or a bad trans input bearing. Either of these requires that the transmission be removed to check but, they can be fixed without completely disassembling the trans for less than $30.

Sometimes a minor rebuild will cure a host of evils if the roller bearings and thrust washers are totally wasted. While a rebuild kit is only around $100, it includes only the bearings and small parts such as thrust washers, a countershaft, rollers, synchro-blocker rings, clutch keys and springs, gaskets and seals. These parts will usually help a box that is noisy or hard shifting but won't always help a trans that jumps out of gears.

If none of this helps the problem and/or it's falling out of multiple gears, the trans is probably in need of a bigger rebuild. It probably needs a 1/2 or 3/4 "synchronizing clutch assembly" and/or one or more of the forward gears replaced. These parts don't come in the basic rebuild kit and they can add up to a lot of $$ in a hurry. You should really have a trusted professional take a look at it at this point.

If you've rebuilt a bunch of manual transmissions, you can generally tell immediately upon disassembly what is need to repair the box. It isn't rocket science but, it takes a bit of experience. If you aren't sure what you're looking at you can waste a lot of time and money on parts that won't fix the problem.

I have not checked anything yet. I have never messed with one of these and I know nothing about them. I found a guy that has done them before and I am going to take it to him. I need to check the shifter first to rule that out before it starts costing.