I have a theory that it might be a Guild bass humbucker, without the chrome cover. I'm thinking of the pickup that replaced the Bisonics in Guild instruments.
What makes me think it might be one is the 2 + 1 screw arrangement, the row of screw pole pieces and the row of flat, rectangular poles. Also the pole spacing is tighter on the Nutz humbucker than the string spacing, even down at the end of the neck of a Fender bass. This is consistent with the tighter string spacing of Guild basses.
Here is a naked Guild pickup, as bodged into a Peavey bass:
The problem here is that I've only ever seen these pickups with cream flatwork, whereas the Nutz pickup is clearly black. The poles also look bigger on the Guild pickup than on the Nutz bass. At a push the modder sprayed the pickup black to make it stand out less, and there is overspray on the poles.