No idea on that one....
I would think the best way to see is to get the parts books for a Challenger and a Barracuda and see if they have the same part #.
I just checked the '72 Chrysler Parts manual. Challengers and Barracudas are listed on the same page and they actually have the same part # BUT they do not differentiate between driver's and passenger side glass. On that page that had all the window regulator info, they make me assume that all the parts are the same for both cars, again not differentiating between driver's and passenger side stuff.
Soooooooo, I dunno how accurate this book is, unless I'm looking at it wrong?
Still nothing on craigslist.org.....