Looks like it might be a 47-early 55 GMC.This is a really cool project, I love it. Please keep posting updates.
I'm near Seattle (Olympia) what's that truck in the first pic, to the right of the '59? I'm looking for that era.
I butt welded them in and made a couple of new pieces for the section on front of the wheelsI like the wheel openings being moved back instead of cutting the frame, That is a good idea that I will keep in mind. Did you butt weld the seams or overlap?