The back side of your GMC should be same as all these Chevs on this site(235/261s). The Chevy truck went to the modern trans bolt pattern in about '51 or so not sure when GMC went to that pattern. But, if you can bolt that 4 speed up your in good shape. You should first copy all the 5 speed 'tech tips' on this site and 'the Stovebolt page'. Tons of great info via the tech tips. Compare the splines from the 4speed to the 5 speed. If all measures the same which I think it will your OK with the pressure plate etc.


It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed