Joined: Jan 2008
Posts: 23,639
Likes: 1,106
From: Mans of NC & SW UT Desert
Bikes: 86 Katakura Silk, 87 Prologue X2, 88 Cimarron LE, 1975 Sekai 4000 Professional, 73 Paramount, plus more
Well, sounding more and more like a 1975. Based on TMar's comment, maybe you can push it out to 1976. It won't be any newer than that. QS is not a date code on the derailleur. Look around it more, it is stamped on there separately from any model # or other info. First letter is year, second letter will be the month (highest month code is an "L"). No "S".