Nice find, despite the condition its still a very nice, great find. Always good to find them in any condition especially nowadays. Don, I think it looks more 1730s maybe 1736. Pic kinda looks close?
My first eyeball-gut reaction was 173x half reale. Looking at Trez's sample picture, the 7 and 3 are very close to OP's find. Crazy to insinuate that the die maker might have made the respective dies for the different cobs. Also, the quality of the planchets and dies fell off a cliff in the 1700s after Mexico City transitioned to milled coinage. Almost like the other mints just said F-It, this is good enough which makes finding a suitable example for a collection a real challenge.
This coin was found at what I believe was a trade site near the Hudson river that was active from about 1670 to the mid to late 1700's. I now believe it is a Potosi 173? (6) half real.