Last winter, while visiting my brother on "the old home place" in east-central Indiana, I hiked back to the woods where Dad dragged what was left of the old combine many, many years ago. I was interested in how the concave was put together and so spent quite a bit of time clamoring over the "carcass". It seems to me that I remember seeing a serial number plate about 4-5 inches long riveted on the left side of the unit, around the area where the straw shakers access door was located. There was a door/panel that was hinged on the top, and allowed you to access the inner part of the machine. Look around that area and see if it's there.
Sorry.....don't think I can help you out with a manual. I talked to my brother about whether or not he thought it might be there in Dad's stuff in the attic, but he didn't think so. Should I happen to find it in the next couple of months (I know that's a long time, but it will be that till I can get down there again), I'd be more than happy to make a copy for you.
Dave of Southwest Michigan