Its been a while since I studied one of my M36A2s, and my memory is not as good as it once was, but it looks like the cab-tandem distance is longer than that of the M36. I suspect that this may be a M35A2 with the rear tandems slid back. The truck bed is obviously based on a cargo bed in any event. Given the extensive changes made in other areas of the truck, I think this truck was "built" by a professional like Boyce or Memphis Equipment. To such a firm, a M36 is much more valuable than a M35A2, and moving the tandems is not a big deal to them. I'm soon to have a tandem change done to one of my trucks, and have been investigating this for some time.
Best regards,
David Doyle