Can't get in Reverse

Sounds like the linkages need adjustment or the ends are worn out. There is a 1/4" hole at the bottom of the shifter housing, disconnect all the shift rods slide a 1/4" pin all the way through the shifter housing, adjust rods so they slide into the arms on the shifter, make sure everything is neutral while adjusting. This is also a good time the remove the shifter and clean out all the old grease and gunk from inside.