Unmarked bottom-gated pieces are the least likely to be able to be IDed as to maker. In the era of bottom gating, the practice of name brand makers producing unmarked versions for different market channels didn't really exist. But there was a good deal of small, under-capitalized foundries using pans of other makers as patterns both back then and later. If there are what looks like grinding marks along the outer top rim of the pan, it would indicate someone using an actual bundt pan as a pattern to make this one.