description sounds alot like a Miyata Ridge Runner I serviced a while back (and about the same year I think) and I too was impressed with how *nice* it was once I got into it...I wonder if the early DBs were Miyata products? Anyhow, my guess it it's definitely a 68mm shell (given the year) and that the 127.5 unit will work fine, I believe that's what I used, but it depends on the crankset. You may need to add a spacer to the fixed side, and I *might* have a pair of cups but try the sealed unit first. good luck.