IIRC, the only thing that has been proven absolutely certain is that the "Paolo Guerciotti" seat stay caps were introduced in 1984. So far, I've seen neither rhyme nor reason in lugwork, cutouts, seat stay bridges, spoon seatstay caps, or decals. That's not even considering TSD's involvement.

I would take every postulation with a grain of salt until enough bikes with reasonably confirmed years of purchase (and even then, a margin of 1 or 2 years for error) could be rounded up and compared with each other. I wouldn't put too much emphasis on the claims of either seller there, Gridplan, unless they had original sales receipts to back their claims.

-Kurt