Looking to beef up the rearend. It is now the weekest link in my drivetrain. In talking to guys I have heard of 12 bolt GMs but also had heard Ford 9 inch rearends are the best way to go? So what are the PRO's and CON's? I would like to know the workout up front in going to a Ford 9 inch.

 

It depends, what car is it going into. The 9" is stronger, but not a bolt in and expensive. A 12 bolt can be built pretty strong, and is a direct bolt in (some of them) into a-body cars. Any a-body 12 bolt also can be bolted into a g-body with adapter control arms from umi.

 

if your going to be changing the gear ratio at all in the future, your better off going with the 9" because you wont have to do as much shimming and what not. If your just looking to replace the rearend, definently go with a 12 bolt. its just like the 10 bolt, but stronger, like marcar said it will bolt right in

 

Thanks guys. Here is a little more info. I am putting this in a 69 Cutlass S. I pulled the 350 out and put in a 455/TH-400 combo. I have been pretty gentle on the car but would like to take it to the local track to see what it will do. Right now I am running the factory rearend and it is starting to leak and figure it would be a good time to put in another rearend.

 

in all actuality a 10 bolt can be built up almost as strong as a 12 bolt...there isn't too much difference between the two.

my 455/t-400 is getting a super beefed up 10 bolt, and i'm having my driveline guy do the work.

 

I put in a Moser 9" August 2006 under my '68 Supreme and love it. Full spool, 4.33 gears, 35 spline axles, drum - drum for around $2200 to my door. Added about 60 pounds over the 8.5" 10 bolt 3.90 that I swapped out and put under the wife's '68, but it's strong rnough to take anythig I'll through at it.

Oh, and it was a direct bolt-in, NO issues!