I have a 1995 Ford F150 XL. It has a 5 speed OD manual transmission. The 1/2 gear shifter fork is worn out. I want to replace it. I have 2 questions:

1) How do I determine what transmission I have?

2) What could have caused the fork to wear out? Could there be other possible problems with the transmission that I need to check out?

The symptoms were the truck would not shift into 1st or 2nd gears but would shift into the other gears.