[Fred T]

If it's popping out of gear it's a tranny problem. Disconnect the linkage and remove the side plate. You will probably find some gear teeth or bearings laying in the bottom.

Actually, the Saginaw 3 speed is pretty easy to work on if you have the factory overhaul manual. There aren't that many shops around that work on manual boxes. Be sure the front and rear seals get replaced while it's apart, and figure on a new clutch, too.

Last manual box on I worked on I ended up buying another from a junkyard about two years later. I had replaced the bearings and seals and fixed a vibration problem. Later one of the gears broke, and the parts would have cost me more than a junkyard tranny.