I'm still trying to figure out how to post the image, but it's available at this image hosting site:
https://ibb.co/dnWBdp
The letter references that the signer is the nephew of former pro football player Monk Gafford, but I cannot find anything regarding this player. The first name appears to be "Dave" but none of my research has uncovered anything. I believe the writer is also a football player since it came with other football autographs.
Any ideas?