Well I hope not but as it turns out 6.66:1 is the diff ratio of Standard Atlas's from new. As we are hoping to do the 2,000 miles of Club Triumphs RBRR in a few weeks I thought it might be time to investigate a ratio change. When new an Atlas was flat out a 52mph but having spoken to Dave Gleed when he was in our shop he recalled the Triumph Service Division (who Dave worked for) fitting overdrives to their fleet of Atlas's (Atlasy?). Dave said that it added another few mph to the top end on the straight and level, but that any sort of gradient was another matter. As far as I could see the only easy overdrive box to fit would be a Standard 10 type but having sold all our remaining core units to Tony L Dean some years ago that option was going to prove difficult in the short time we have before the RBRR. So out with the diff and a strip down was on the cards. I already knew from the parts books that a lot of the guts were 2000/2.5/TR and so it proved to be. In went a nice 2000 4.11:1 CW&P set I had on the shelf and the diff is back in the Atlas.