I can't help you on this one... Pretty sure Jeffy can.
My 2 cents... call it coincidence... I bought my Jeep and drove it for a year until I thought to change the manual tranny fluid. I did so and not more than 100 miles later it stopped going into gear. I got another tranny and gave that broken one to the guy I bought the rebuilt one from. So I don't know what was wrong with it.
So, coincidence???