There is an obvious difference in the length. The 41-46 cabs are about 2 inches longer than the 39-40 cabs. That makes the running boards about 2 inches longer as well. It might be possible, it might not... probably depends a lot on skill level.
It looks like its just longer at the fire wall.Im using a 39 cab on my 46 frame.The only differance i noticed was the small step out on the lower cowl were the 39 fenders but up against.Im hoping this all works out as my 46 cab was crushed by a big oak in a storm a few years ago and the 39 cab was all i could find to replace it.
