Alright well i got a 1988 Jeep Cherokee/Pioneer with a ax-15 manual tranny. It only grinds going into 3rd the most,and sometimes 2nd and 4th. However once it's in gear it drives fine. And also it will randomly not go into any gear and i have to turn it off and shift it through the gears with it off and then crank it up and keep driving but it's left me stranded now so i'm trying to find out what it could be i know it's fine on fluid it doesn't leak. Please let me know any useful information.

 

You would have to tear down the transmission to be sure of what the problem is. It could be worn bearings, worn syncros, or both.