The 1941 GMC has a 4 bolt flywheel to crankshaft mount. The 1956 235 has a 6 bolt flywheel. You need a flywheel from a 1954 or earlier 235 if you are going to retain the 6 volt starter. It needs to be from a 3/4 ton or larger for the flywheel to be drilled for the larger clutch.