Hello Endo I do believe I have have some originals . But I fitted repro ones . The quality is ok
The most important aspect is the screw socket on the body to accept the lens securing screw. The good ones have an embedded brass threaded encapsulated nut.
The screw is threaded not a self tapper. The black flange should be pliable as poss. I think mine came off eBay but the ones in Andys link appear good especially for that price !