first one I've seen with a shoulder harness would be a 69 , and I don't think it was manditory yet , so I'm not sure if they all had them. My 70 vert doesn't have them so I'm guessing they all didn't .
I know the later years had the shoulder harness but what I am talking about is some earlier cars I've saw had one thats near the coat hanger hook, hidden under the headliner...ya had to poke around to find it...i believe i saw it on a 67/68 though...and I would like to mount some in my '66 to go w/ my new 97 stang seats...but if they don't I'll just hafta wait for the rollbar to get 'em