Major change in the 41 over the 35-40 frames. The 41 Ford pickups also used the 40 style frame. I'm using a 39 car frame in my 40 pickup build using a 46 1 ton cab. It's the same cab used in the 1/2 ton pickups except the fuel take is behind the seat in the 41 to 46 cabs. Easy fix.
The Jalopy Journal
