Well, so much for my head badge theory. The website for PDM teams for 86 to 92 show Concordes with decal head badges for all of those years. Here's a good one of Greg LeMond on a Concorde,
http://www.dewielersite.net/db2/wiel...cannen0003.jpg

My Corcorde has the little metal head badge, but also rear brake cable routing through the top tube, so again I'm guessing early 90's. Maybe some shops/frame makers were using decals and others using metal head badges, all at the same time.