Hp difference between a 9 and a 12 is minimal.Like 3%,is what Strange claims,but a 9 will probably be lighter.But who cares about 10-15 lbs of rear end weight on a "street" car?Everyone claims a 9 is real strong,and I have one in my car cause my buddy gave it to me and it was already narrowed to what I needed.Used to run a 8.5 10 bolt with street gears and stock 28 spline axles.Drove it on the street for about 7-8 years like that,then took it to the track for about 100 or so 1/8 mile passes.Car is 3400 lbs(don't get me started,Earl
)and has about 625+ HP.Never a problem with the "puny" 10 bolt.I'm not impressed with the 9,to be honest.I know you can swap gears fairly quick(no quicker unless you can afford a whole nother pumpkin) and they do hold up,but they seem thin to me.You can't brace the spool bearing in them like you can a 12 or Dana,no way to get to them.Pinion stem seems kinda small(10 bolt and D60 has same dia. stem,10 bolt has one extra spline)only thing I think they really got going for them is the bearing support for the rear of the pinion(next to the ring gear).Bearings are smaller than what was in my 10 bolt and bearins cap are smaller,too.Plus they look like thay are cast from some pretty cheesy 3rd world junk,real poriuos(think I spelt that wrong
ops: )I honestly believe stock for stock that my 10 bolt was a far better rear than my 9".12 bolt will be even stronger.Had it to do over,I'd definitely go Dana.JMO