Best to date 60' on bfg drag radials is high 1.5's or low 1.6's.The stock rear seems to take this abuse without to many problems.Now if a person could find a Dana 44...this would be a stock replacement that is much stronger!
Only problem with the stock 9 bolt is if the posi take a crap your out some major dollars for another one.The 9bolt uses conical type clutches and they are not replacable.What kind of times are you running?