Thank you all for the quick response. This new info (the Aztec pattern was particularly helpful as an identifier) when considered along with my previous research leads to only one conclusion. The bike in question must be a U-08. Although built in the early seventies ( the presence of both group/series 1 and group/series 2 decals places the manufacturing date in the few years ((I think it was 70 to 73 or 74)) when there was an overlap and both types were being placed on bikes ) and often referred to as low end and entry level I have found it to be a surprisingly comfortable ride. Maybe my opinion is biased since discovering that the bike and I are roughly the same age but after having ridden some friends newer more modern bikes I think the UO-8 holds up very well.
Maybe it's symptomatic of some type of midlife crisis but having been an avid rider in my younger years the idea of getting out and riding this 40 year old bike amongst all the new high tech rides really appeals to me and as a result of this garage sale encounter my passion for riding has definitely been rekindled. Next I think a full restoration to all it's former 70's glory is in order and I will be keeping a sharp eye out for a a PX-10.