Today I saw a mid-80's Trek with a very peculiar post clamp lug. The seat stays appear to be butt-welded--fast-back style--to the lug .....and then there are a pair of 1/2" long, additional lugs(or maybe just collars) 1&1/2" down the stays. Each of these collars have the TREK name cast into it. As do all the other lugs and the BB. This BB is the same as on my '85 720 & 770---- but all the lugs are different. Dazzling silver metal-flake paint job. With red decals:"500 series", "TREK", & "USA". No tubing clues. All Shimano 600. 22"or 23" frame. It will be for sale but the owners are not in a hurry.
Anyone know anything about those strange lugs?
Calvert Guthrie
Kansas City