What adapter is this?

I have a Polaroid back for an unknown camera. The flange is 5" square, but with a small notch at two adjacent corners along the long side of the adapter. It's good for Fuji film, but I don't have any idea what camera it fits. Any ideas?

Galvin?

According to this, I seem to have the Polaroid adapter to a Galvin 2x3 monorail camera. Anybody own one?

I was going to guess a 2x3 press camera or the like?? You can probably mount it to any 2x3 mount, the rails look pretty standard. Other than that, you can try to remove the flange and repurpose the back. could work!

I don't own this one, it's PHSNE's. I have a number of backs myself–with and without dedicated flanges, however, so I don't need it. I'm just surprised at what it is given there was no Galvin camera in the collection that included this back. It was a big lot of cameras that had belonged to a man who never told his wife that he was collecting. There were literally hundreds of good cameras in the house and garage after he died. His widow has entrusted PHSNE to get rid of them. We've had three auctions and sold much of the stuff quietly on the side, netting her thousands of dollars. I'm doing what I can to help out.

This collection staggered the mind. There were cameras everywhere and the wife, a seemingly intelligent and alert woman, was oblivious to them. He even hid a Leica in the charcoal grill in the garage. I found myself wondering what else he hid... but that was none of my business, of course.