I had also thought that it was just a difference of finish, but Shimano 600AX and Dura-Ace Ax are actually quite different. The design is the same, but the actual parts do have differences. The seatposts on Dura-Ace are better finished, but it's hard to photograph. I haven't tried, but I think the parts would interchange. The Dura-Ace brakes are on much narrower bodies, to the point where the wedges can't be interchanged at all. I didn't go beyond that, as there wasn't much point. The finish is a bit better here as well. The 600AX rear derailler I have isn't well finished at all, and I'd be surprised if the Dura-Ace was actually the same.
Steve Birmingham Lowell,Ma USA
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net> Subject: Re: [CR]eBay outing: Complete 1980 Shimano 600 AX group Message: 5
I've never seen good pictures of a complete 600 AX gruppo before, but I have a mostly complete DA AX gruppo. Other than the markings, I can't see any difference. Design looks identical and if there is a difference in finish quality, it isn't obvious.
So what was the difference between DA AX and 600 AX?
Regards,
Jerry Moos
Big Spring, TX