Ya you guys figured it out already. Only a few were made, and I think profosist also have a few of these too. He said there were also problems wit fitment of the stabilizers, not with just the thickness, but the positions of them were slightly off and that caused problems. You might have to dremel off more than you'd think. It has compatibility with Filco only, and nothing else.
Other than that, I don't know much more since I was not the one that designed it. I wouldn't be able to tell you how exact all the positions are.