None of them. I'm guessing it's based on Weber's 5A40. Which is essentially a Super Reverb circuit crammed into a tweed Bassman-style cabinet. AFAIK, the only difference, circuit-wise is the 6M40 comes with EL34 tubes, which I just swapped back to small bottle Phillips.
The gold chassis looks really groovy on this thing.
Oh, and I figured out, replacing filter caps isn't going to be as bad as it looks. If you dis-assemble it one cap at a time, and then rebuild, you won't need to pull the board.