welcome to the site! Yes, the cab is the same from 1/2 ton-2 ton. So is the hood. Fenders are wider and the grill is different.

I believe the 1 1/2 ton and 2 ton fenders are the same (except maybe holes for the side emblems).

It depends on the parts you are looking for. Rock Auto should have brake stuff like hoses and wheel/master cyl kits. Cab parts, Americanclassic and Jim Carters both have a number of cab parts that are the same between pickups and big bolts.
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Mike
1955 Chevy 6400 ex-flatbed (no bed now!) sold September 2023
In the Stovebolt Gallery
1958 Chevy 6400 flatbed W/dump
In the Stovebolt Gallery
1959 Chevy Suburban Owned for almost 20 years, Daily Driver -- sold May 2016
In the Stovebolt Gallery

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