See my post above for a pic of a Colorado TG. TG stands for TIG weld, which means that the tubes are welded directly together without lugs. There is no performance or quality penalty and the result is slightly lighter than an identical lugged frame, although C&V collectors preferred lugs for their aesthetic value.

Here is the 1994 catalog that explains more.

http://www.retrobike.co.uk/gallery2/...2_itemId=15536