Reluctor ring
Rod, this is what I found out. The reluctor wheel is held on to the carrier via a slight press fit. The replacement carrier you have should be the same outside diameter as your stock carrier. (hopefully) After you mount the ring gear on the carrier you simply set the reluctor wheel onto the carrier and tap it down with a rubber or brass hammer seating up against the back of the ring gear. If the aftermarket carrier is not the same size. There is a company that sells a pickup and converter so that you can still have your speedo. The first choice is cheaper. If you need the name of the company let me know and I can get it to you. Hope this helps.