There are a few C-80 owners on here. One is a Tandem Axel Dump, which should still be over at the Gallery. It was an original 409 truck.
I used to drive a '62 GMC 6500 which is the equivelent of a Chevy C-80. It was a 32,000 lb GVW Flat Bed Dump with Air Brakes. Also had Spoke Wheels and 10-20 Tires. Not sure what Wheel Base it was but it had a 16 Ft Bed on it.
Bill