Hey lower50's,
About your Chevy vs GMC question... You might find this interesting, a GMC wiki:
https://en.wikipedia.org/wiki/GMC_(automobile)
Here's a little snippet:
"Starting in 1920, GMC and Chevrolet trucks are virtually identical except for the grilles and nameplates, though their differences have varied over the years. From 1955 through 1959 small (less than 2 ton) GMC trucks with gasoline V8s were equipped with Pontiac V8s. Chevrolet trucks were marketed towards private ownership, while GMC was focused towards commercial uses."
ps, nice job on your floor.