What I have is a 66 single headlight 520 and I am looking for a replacement cab. I was told somewhere that the 520 cab from a 65-66 was the only option I would have however I have a 71 521 as well and when I take measurements of its cab it looks like they are the same. I could use a cab from say a 67 -71 just fine maybe. I haven't even looked at engine swaps yet as I hope to keep the j13 that is currently still running and in the 520.
Oh, and I am out in Saint Helens, OR