[lower50's]

Here is some info I found:

Across the fender width is:
3000's 72 5/8"
4000's 74 7/8"
5000, 5000s 77 9/16"
6000's 74 7/8"

The length of the front end fire wall to bumper is:
3100 51 1/16"
4100+ 56 1/16"

Frame width:
3100-6700 are all 36"

Height of C frame and thickness:
3100 5 3/4" 9/64"
36-3700 5 27/32" 3/16"
38-39-4100 7" 7/32"
44-45-50-51-6400 8 7/8" 1/4"
6700 8 15/16" 9/32"