Are you asking for the gm 8.2 BOP rear that came in firebirds which is limited in available gear ratios these days ?
Other than that there are a whole plethora of choices like the GM 8.5 which has a vast choice of parts and gear ratios that is modestly priced.
Or you can spend a couple thousand on ford 9 inch, dana 60...etc.
Gear ratio will depend on rear tire size and if you want to cruise on the highway at 3500 RPM or more.