Strength of the Spool?
There are super lightweight and aluminum spools that wont hold up to heavy cars/1000hp/7000rpm clutch dump drag racing but you can pretty much consider a standads spool unbreakable in these cars..Yes a spool in a 12 bolt will be much stronger then a posi in a 12 bolt, plus they are lighter and cheaper and you will never have to worry about your posi going out. Bad part is they arent a real lot of fun on an everyday car and depending on the situation can be pretty dangerous.

