I picked this bike up at an estate sale today for $12.50, and need some help IDing it... it has shimano thunder bird derailleur, shimano shifters... pedals say they are made in West Germany... has a weird “WRN” stamp on the front fork... handle bars say Schwinn but the serial number doesn’t match up. Any ideas?

i can’t post a URL directly as I’m a newbie. So here is the link to photos...

....imgur.com/gallery/Lmdebxi