To me it looks like an early model 39 (38 inch cut) as used on the 110/112 square fender tractors. The model 39 was also sold for the 200 series tractors, but I think by that time (1975) the exit shoot was a hinged piece rather than the integral type as shown on this one.
Yes it should work on a 210, but the long arms that attach to the tractor frame don't look right. They would have a couple offsets (bends) and spring loaded pins for connecting to the frame. The Left&Right lift straps appear to be OK. You also need the correct draft plate to attach to the front of the tractor frame. This may get tricky if you have to search for one. Apparently, early model draft plates were not interchangeable between model 39 and the larger model 47 decks made for 110/112 tractors. Somewhere along the line Deere made a change to the deck that allowed the draft plate for the model 47 deck to also fit or adjust to the newer model 39 deck. The yokes on the draft plate adjust to control the forward tilt of the deck, serves as the support for the front of the deck, and lets the deck raise and lower straight up and down so to speak.
There should be a metal tag riveted to the right rear wheel mount or near it. The tag has the model and s/n for the deck. If possible, get the numbers from it and note if the tag is brass or aluminum. That would help identify it more accurately.
This one looks a lot like the one you are looking at. Don't know what tractor it was on, but the s/n tag is located on the front on this one. Note the shape of the arms. Draft plate is also shown. They both appear to have original black and silver stickers, so it's 1969 or newer I think.
The model 38 3 blade deck ('64 & up) as used on the round fender tractors are straight like that IIRC. Eventually the model 39 was offered as a replacement for the model 38 but I believe straight arms were available to fit the tractor. The double stack pulley is also smaller in diameter on the model 38. The blade drive pulleys might be smaller too, but I don't know for sure. The model 38 for RF use must have been a different part number assembly if an assembly actually existed.