Rear differential efficiency

[Greg Reimer 7376]

Once you put a spool,good axles, wheel studs, the proper bearing kit and steel web caps in the 8.5" 10 bolt,(which you do to any race car rear end,anyway),it probably has 90-95% the strength of a 12 bolt. I don't think the weight is more than 5 pounds difference, but cost and availability is a real factor here. I wouldn't pull out a 12 bolt in any of my cars for a 10 bolt because they are there already,but if I had the 8.5" 10 bolt, I would go no further in my search. One advantage to the 12 bolt is the availability of gear ratios is larger.