My guess on this one, based on a few connecting hints, is Regal-made for wholesale. Vernon (in Jake's example) is a Regal brand and I have seen that particular headstock pictured on a flatback two-point mandolin in Bob Carlin's Regal book. I don't see any guitar-shaped mandolins in that book, though.

Another one is pictured in this thread.

BTW that headstock design (and similar) while used on Martins, Vegas and other American mandolins, was also used on some Italian mandolins as well, so that is not particularly conclusive.

And, as others have noted, that tailpiece was common on multiple brands and also available as a replacement part.