I wish you the best of luck in finding the vinyl you are looking for. I have spent years looking for the replacement vinyl for my 71 Javelin without much luck. However, what I will probably do is that I found a vinyl shop who can come very close to the grain of the existing vinyl. You would have to look very closely to detect the difference in the grain pattern. If you cannot find the factory correct vinyl replacement for yours, would suggest that you look at what some of the shops that install vinyl on cars would have. Sorry, but I have not seen or heard of anyone who can factory match the vinyl that AMC had on their cars. Just another case of AMC kind of striking out on their own and coming out with patterns that not too many shops would handle. And yea, I guess that age would have something to do with it
Call 800-363-8804, Legendary Auto. They have them in black or white in both the 71-72 "T-top" style and the full top for the 73-74. It is available in Levant grain vinyl which is correct for the 73-74. (71-72 use Boar grain which is also available.)
I'm glad I was able to help you guys out. If you ever have a question about upholstery just drop me a line. I own an upholstery business that specializes in muscle car restoration. We do a ton of Mopars but also are currently finishing up a 69 AMX. I own a 69 Javelin so I was able to find many of the parts for the AMX since the restoration shop we are doing the work for is mainly a Mopar shop. You can reach me at sewcleanupholstery@sbcglobal.net.
You can also see some pictures of some of the cars we have worked on at picturetrail.com/sew-clean