There are numerous parts which need to be checked for wear. All of the shifter rod ends and the holes in which they fit, the bell crank pivot bolt, the shifter box case (aluminum).
I would start by removing the shift box cover and make sure that it is lined up correctly when the transmission levers are in the neutral position. If everything in the box is not lined up, it may be as easy of a fix as adjusting the shift rod length at the shifter box arms.
If all of these items don't fix your problem, make sure that your rear engine mounts are like new. Any movement in the engine due to worn mounts will change the geometry of the shifter linkages.
Carl

Last edited by 52Carl; 05/23/2016 10:33 PM.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission