Which one is better for longevity, which one is easier to install, and also which one is cheaper?

 

To say either 12 bolt or 9" and the word cheap in the same sentence is a oxymoron.. Both are significantly stronger than the stock rear.. Longevity really depends on who's driving it and the kind of power, clutch, etc your running.. It all can swing it either way.. Expect to pay around 2K for either rear... And from what i have seen on here used one's circulate for about 1500 or so... IMHO a 9" is the stronger of the 2.. but i may be biased...

 

I always hear moser 12 bolts breaking from guys putting out a lot of power but never any stories of the 9", then again I probably don't get around much, i'd go 9".

 

what is the weight difference in the 2?

what is the difference in drivetrain loss in the 2?

 

You should do a search for it.

 

the 9inch is stronger i know i have one. if you have an auto then go with a 12 bolt it will hold, but if you have a m6 then the 9 inch is the way to go. you will lose a little more power through the 9 inch but it will be worth it.