Don't know about a C inside Diamond, but this was stamped on my '51 Chevy 1/2 ton Pickup frame above the front axle on the left side.
As far as sloped sides on the pickup box, GM went to flat sides in '54. Don't know about the other manufacturers. You could do an image search on the web and find that info out.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
