I had a similar issue, went for a nismo one in the end. I did have an old isotta one knocking around but the screw on thread type didn't look so good above the gaiter. The nismo one case with a black plastic cone which above the gaiter to tidy it up. I was also expecting it to be threaded but its just got some plastic fixed inside which you thread onto. Also the shape is different but getting used to it now.