I wanted to do everything I could to improve my shift linkage before we dropped my trans for a rebuild so that when the new trans goes back in it will feel good right from the start. I searched and printed every thread I could. I spent Easter Sunday replacing the bushings, scrutinizing the shift mechanism and basically poking and prodding. My firewall bushing was pretty worn. After putting everthing back together I could barely pull the shifter out of 4th. Finally figured out that with the new bushings the linkage was rubbing against the end of the bolt for the seat belt. Shortened that bolt and it's like magic.
I wonder how long that bolt was effecting the shift into 4th? Just another stupid thing to look out for.