8.25" rear axle and disc brakes???

yeah for 10 inch drums. double that number if you want 11inch drums. most applications 10 inch is fine though. plus if you cant do the work your self labor is also a factor.

drums or discs...doesnt really matter, most of your stopping power will come from the front brakes. rear discs are pretty much just for the looks for me because i really wont be racing my car, just cruising.