Has any of you ever seen a banjo built on Fred Gretsch's July 14, 1891 patent? I have a banjo that is very similar if not made by Gretsch. It has no markings except some writing on the head by a previous owner. I have few pictures of it is on my tablet, I'll post them later.
It looks pretty much identical to me, even down to the number of brackets. Your's has one more bolt at the end of the wooden part which I assume is for the tailpiece. Even the tailpiece looks the same as the drawing. It looks like yours has the clamping ring that he describes in the patent description (No. 14). I'd say it is definitely a banjo made according to this patent. Since the patent says there is no model, maybe this is it.