1940 Frame Interchangeability

[DBF 30]

I have read that 1935 -1940 passenger car frames are all identical. My question is, will a 1940 convertible car frame be interchangeable with a 1940 truck frame?

My 1940 convertible frame will require quite a lot of rust repair and I need to know what the full range of frames that I could use as a direct swap that would be a complete match with the original. I am aware that the truck does not have body mount brackets but don't know if the rest of the frame is the same as a car frame.

Thank you for your help!