The 53 frame is basically straight from front to rear with a slight hump over the rear axle and tapers inward to the front . The front axle had no hump over it. The 76 frame will have a hump over both axles. here is a picture, the frame in the background is a 53 3/4 ton and the frame in the foreground is a 73 3/4 ton.

1953 Chevrolet 3600
Fried Green T'mater (Vern)
In the Stovebolt Gallery
Caution: Political Statement
Man who runs in front of car gets tired, man who runs behind car gets exhausted.