So I answered my own question recently. I just purchased a set of original front comfort weave upholstery for my mach 1. The seat backs are indeed dated on the inside headrest portion. As for seat bottoms, I could not find any anything except for some letters and numbers. I'd post some pictures, but I spent half an hour trying to upload to my gallery and couldn't without the webpage crashing.
Anyway, just thought I'd share in case anyone stumbles on this thread.
Edit: Now we're talking... I guess the images from my camera were too large. I updated with the pictures of what I'm describing. Happy New Years!