7777,
those numbers look like part numbers to me, not mast numbers
did you check on the side of the outer channel for any stamped numbers? they are usually stamped on the outside about the same height as the tilt cylinder eyelet on the right side, or left, i cant remember for sure which side.
sometimes on older ones the number is stamped on the crossbar at the top but usually you see the channel part number there.

you might have to do some scraping if its been painted before

good luck