Being that this one has the recess for the cap, but not the later style silkscreened logo, I'd guess 83 or 84, maybe 85. Can't remember when the caps started. These really were the same from ~ the mid 70s to the mid 80s. The engraved logo started around 1980 or so. The aero mod 78 version came out in 78, big surprise.
Silkscreened trademarks were basically unacceptable until the mid to later 80s. Engraving was expected in quality parts. Eventually the consumer was trained to accept cheap printing of company logos.