Just my opinion, but I think the "P" cases are for bragging rights. I had 2 of them and sold them both. I presently have an open 3.36 rear in my 409 powered '62. I also have a stock posi unit sitting on the shelf. Not sure how I acquired that. My plan is perhaps some day take the rear and posi unit to someone reputable and let them mate them together. I'm sure some grinding will be involved from what I read, but personally, I don't care. I also wouldn't have a problem using an Eaton or Auburn posi unit in an original open rear. Again, some grinding involved, so what?? If anyone is happy with paying that kind of money for an empty "P" case, then I'm happy for them, Carmine.