1950s 2 ton?

[mongocanfly]

I don't know why but I've got a hankering to build a big truck. I tried to do a search on this forum but it takes me off on a google hunt. If I'm right I under stand that the 1/2 ,3/4 and 1 ton( aka 3100, 3600, 3800) 47-54 cab and front ends are the same deminsional size. My question is when you jump to the 1 1/2- 2 ton (aka 4400 6400) trucks what are the differences..if I understand right all cabs firewall back are the same for all 1/2-2 tons but firewall foward is different. Does anyone have the measurable differences in these cabs. I am looking at getting a 4400 or 6400 cab to build.