Hello. I am new to the forum and searching for answers. I just a acquired a 01 f250 7.3l with a 6-speed manual transmission. The truck has 80k on it and the seller told me it had a bad transmission. I started the truck, which had been setting for 4 months, and it drove great for about 10 miles or so. The truck then got stuck in 5th gear. The gear shift will move freely but will not shift to another gear. Clutch seems fine. Any suggestions on where to start? I'm not sure why it drove fine for several miles with several shifts to all the sudden stuck in gear.

 

How does it shift with the engine off?

Have you tried checking the fluid for metal?
There is a magnet in the transmission aft of the drain plug that you maybe able to feel if you finger fits in.

 

I just now the truck to my garage. Truck shifts fine with the engine off. I managed to get it back to low gears to get on the trailer. I will check for metal. Thanks for the reply.