I picked this up last night and am pretty excited that it'is my size 56cm. Original owner was recommending Goodwill but thankfully his wife recommended posting it on CL. It was listed as "15 speed Schwinn" Owner was in the service and used it for tours in mid-west with his service buddies - possibly why he chose green.
Everything is very dust/dirty but I can see that after a complete cleaning I'll have a nice vintage touring specific bike, of which I have been watching for.
This pic is of the the original CL post as I have not taken pics - like to admire as-is till I get time to work on it. Unfortunately its not of the business side so I'll get some of that side.
The serial number is 6B21351 and is stamped on the lower center of the headset. Sticker says Columbus and it has rack braze-ons on forks and rear. It has biopace crank and canti's. Brake levers say GC(?) and DR's are shimano with no model visible.