I'm pretty sure that is a late 70s/early 80s A series heavy rock crash but it's difficult to tell for sure because the Zildjian stamp itself is kinda hard to see. The only time I've ever seen those big bold rounded letters that say ROCK with the star in the O was on these. A trick I learned on cymbalholic back in the day: put a pinch of flour on the stamp and rub it in real good with your thumb then give it a quick wipe with a soft cloth, this makes the stamp very visible without damaging the cymbal.
Zildjian themselves are usually pretty good with this stuff, send them an email.
Keep in mind that these are just labels... One man's heavy crash is another man's small ride