masnitram, great job on all the info you've been able to provide. I can't seem to find the article which has been mentioned about the clothing store in Wheaton, IL.
I looked up the address and found it is on Hale.
http://www.dexknows.com/business_profiles/gaede_s_mens_and_womens_apparel-b179689
I'm very local to this area, though not in Wheaton myself.
Here is what I can offer about the immediate area near Hale in Wheaton.
This is very near Wheaton Bible College.
The shopping area is not a big shopping area. It's a smaller much older downtown shopping area which would mostly be used by locals. (the towns along the train stops are the ones which have 'real' downtown area's).
It is also very near the Illinois Prairie Path which is used for biking or walking. This was at one time a single track train route of somekind. It's been a path since the 70's. I used to ride through Wheaton all the time as a kid.
Also near by is the train station which is now called Union Pacific/West but in the 70's was called the Chicago NorthWestern.
http://metrarail.com/metra/en/home/maps_schedules/metra_system_map/up-w/station.WHEATON.html
The train currently runs west to Elburn, but the last two stops, La Fox and Elburn were added long after the 70's. Geneva, IL would have been the furthest west stop in the 70's.
For this JD to purchase clothing in this area is odd to me. It is not an area with many clothing stores... nor is it near what is considered a main shopping area. The only reason I can think of for this young man to have purchased clothing here was either a stop on the train and getting some kind of assistance from someone at the Wheaton Bible college? When I say it is hardly a shopping area I've been local to this area all my life and had never heard of this store. It is not near the local malls nor was it along any of the main roads which might have a K-Mart or similar style store which was around in the 70's. Though those types of stores would have been appx a 10 min drive from this location in Wheaton.
Now, back in the 60's or 70's there was a Sunnyside boys home in Wheaton.. but I would have to do some digging for exact location. I believe it was on Orchard but closer to Butterfield/Rt 56 - and I think our JD is older than someone who might have been in this boys home.
Just food for thought.... Not sure if it helps or not but thought I would share.
ETA: I wonder if the bike was stolen too.
I think the Wheaton Library is not too far from this location either. Did they say which library the library books were from?