frame differences in cummins trucks?

[furious70]

I've heard cummins trucks run on a 7" frame and that the rails are 1" wider at some point, any truth to this?

[Thornbird]

Not sure if i'll be much help here, but thought i'd jump in..... Going by what the brochure says, the 2500 and 3500 have a larger center section on the boxed frame rails- 7" for the 1500 and 9.5" for the 2500 and 3500. "Chassis cabs get a secondary c - channel crossmembers, rear side rails and an 11" center section".
That's from a 2001 brochure. Nothing stated about frames being different from a gasser to a diesel.
Not sure if that helped......