55-59 stepside bed dimensions: 88-98 frame?

[Miles B]

Hi

I'm looking at buying a 55-59 stepside, and want to put the body on a GMT400 rolling chassis. I've looked at sgtusmc's build and it looks like the cab shouldn't be a big problem. The front track widths:
55-59: 60.5"
88-98 C1500: 63.2"
88-98 C2500: 62.6"
88-98 C3500: 63.3"

I'm just concerned that the stepside bed might have a little intereference with the frame rails. I don't think it will, because the stepside beds seemed to be about the same from 55-87 and I think the 88-98 frame is actually a little narrower than the frame it replaced. But if anyone has any measurements of the inside clearance of a 55-57 stepside bed, I can make sure.

Thanks!