On the '55-'59, the feul lines will be the same, 1/2 through 1 ton. The frames are the same width and have the same crossmembers from the cab mount forward. The 3/4 ton and long 1/2 ton frames are identical. I don't have it handy to scan in, but I do have a copy of the Assemble Manual, there is a drawing that shows how the lines fit. I can get the pic up for you, if you'd like to see it.
