Eaton makes a reasonably priced new posi unit that alot of guys posting here like. I put nearly a grand in the posi I built last year for my '68, so be ready to burn some dough setting it up, but would be well worth it in the long run. Your 3.23's would be a nice street gear, especially with a 455! 3.55's would be great with a 400. I would use a Richmond gear if replacing old set. Just my .02
