Ben,
I'll have a look at the plate as soon as I can get to it, but if I take a picture of it, it will be a while before I can post it, as I still use a film camera and I would have to finish the roll, get it developed, and scan the print before I can post it. As for disassembly of the motor, if you're going to be working on it that's OK. I just don't recommend taking it apart just to see the date stamp on the armature. If I remember correctly, the nut on the fan will have a standard thread since the motor rotates in the opposite direction from the later models.
Jeff