If you don't care to keep it 100% original with the BOP rear end, it might be cheaper to find an 8.5" GM rear end from a 72 - 75 Chevy Nova or Pontiac Ventura, It will bolt right in with only shortening the driveshaft one inch. They are very plentifull and cheap, lots of aftermarket parts to make it very strong if needed, but it is all most as strong in stock form as a 12 bolt. I have one in my 69 with 3.42 gears and TH-400 and it is just perfect for me on the freeway