Ok, so this is what I bought:
https://drive.google.com/folderview?id=0BzvtJeD-iR1iZkpKUDh0Q04xS0
I'm guessing this is the TTE50 from the late 80s/early 90s, but I'm not sure. There isn't any stamps, stickers or markings other than the six digits on the neckplate.
Seller had some information...