I can tell you it is not a 50's chevy truck frame. I have done lots of work on the 47-54 and 55-59 truck frames. I would think it is a Studebaker frame. The crossmember has mounts for a 6 cylinder and looks to have a spring pockets for a Studebaker, the few that I have worked on had small diameter springs. Most truck frames have pretty straight rails with very little elevation change in the side profile since they don't have a very low ride height.
We can all be sure it is not a Camaro.....
Rodger