Its a Jetstar 3. I think its later than '63 or '64, there is no evidence of a low band across the grille. My guess is '68 or later as it does not seem to have a brown belly.
The tag should be below the platform on the right side of the transmission case behind the brake pedals.
If you don't see that tag, there should be an engine tag either by the starter or on the other side of the crankcase, give us those numbers and there are a few people on here who can tell the year the engine built from its serial number. The engine serial number and tractor serial number will be different.