8.25 solid pinion spacer.

Got a 8.25 out of a 73 Dart Sport 340 going in my 73 Duster. Got it stripped down to blast and powder coat. Figured I might as well freshen it with bearings seals ect. I want to get rid of the crush sleeve with a solid shimmed spacer. Looked on Ratech and their # is 4114 for the spacer kit. They give dimensions of a little less than 0.5 inch. My old crush collar measures 2.975 used. It looks like one for a 8 3/4 489 case. What gives? got a part # Emailed Ratech still waiting for a reply.LOL