'31 Dodge? IIRC, my guess not reproduced. You could try the DBC or AACF forums. Someone might have one. Might be you're going to have to fab one up, though.
If it is for your 33 Dodge I don't think there is a reproduction piece available, you may find something in Hemmings or you might just fabricate a replacement. HRP
I was hopeful that I could find a place remaking the board, but really what I am trying to figure out is what kind of board material is supposed to go under floor board for heat dispersion. I am sure I will have to fab my own board up to work.
There are several manufactures of peel & stick material that helps with keeping the heat out, I recently used a product called kilmat, it works great. HRP