I hear that these are the two tough rear ends...but what are the differences between the two? I know nothing about either one. Which is stronger, cheaper, recommended etc??

 

i heard a 9in doesnt have abs where as a 12 bolt u can still have abs.i also hear a 9 in is stronger but their both relativly bulletproof.

 

The 9" isn't avail for 3 channel Abs car's.. Only for those w/ Traction control.. I.E reluctor's on the axle's.. But!! there is a way of making it work.. Do a search and you'll find it being discussed... As far as strength.. The 9" is by far a superior rear end... I have seen/read many a broken noisy 12 bolt.. they are both priced closely to each other.. but the 9" is the better buy.. IMHO.. 12 bolt's are great for A4's though.. they tend to be a lil bit easier on the rear's..

 

where can yyou buy as 9" and are they easy to put in?

 

You can buy it in a few places.. They are no harder to install than a 12 bolt.. Which is almost plug and play.. Just need to have the backing plates off of your old rear and the new bearings pressed on the new axles.. also you'll need to get a few nut's that moser don't inlclude w/ the rear.. Why i dunno.. But they are fairly easy to find at any nut/bolt store..

 

9 inch has more rotating mass.

 

thanks for all the quick answers and replies...is more rotating mass a good thing or not??

 

not a good thing, it takes more power to turn it