Mike
If it will help, some of the classic truck vendors sell MC replacements. I ordered one from Jim Carters for my '46 a few years ago. Since then I have seen them listed by BowTie Bits and Chevs of the 40's. These are 1"" bore, which would be correct for '37 1/2 ton.
Another thought, since the PO changed the MC to a ford mc, were by chance the brake lines and brass fittings changed, (re-sized) too? I know zip about any potential differences between the two, just wondering.
