rear end questions

[shawn_s]

Hey guys, I have a few questions at a project im looking at starting in about 6 months or so. what im looking at doing is taking a 79-81 trans am and swapping in a LS1/T-56 combo and hoping to put out between 400-450 hp. this is the first type of project like this that i have ever done so theres a bit of a learning curve.

So i have a few questions about the rear end, i dont have the car yet, but i think it came from the factory with a 10-bolt. I was thinking about upgrading to a 12 bolt set up, probably from Moser, and i noticed there are alot of aftermarket rear ends based on the Ford 9", so how does the 12 bolt compair to the 9".

and my other question was about axels, more specifically, splines. looking at the moser 12 bolt i noticed they offer 30 and 33 spline axles, from what i understand the 33 spline would be better/stronger because of more contact points, correct?

and if anyone could give me any other info that would be great.
thanks

Shawn

[ProdigyCustoms]

Your stock rear can be builkt pretty strong. Those 8 1/2s are tough as nails. I have a friend running high 8s on one with a spool in it!

[shawn_s]

Thanks, have any parts suggestions or anything?

Does anyone else have an opinion on this?

[wmhjr]

I'm building a '66 GTO Vert w/poncho stroker in it. Probably just at or under 600hp and over 600tq. TREMEC TKO600 5spd overdrive. I went with a Moser 12 bolt 3.73 Detroit TrueTrac rear end. 33 spline axles, 1350 yoke, performance rear cover. Ford flanges and drum brakes, no C-clips, great unit. You can see it as delivered at:

https://static1.pt-content.com/images/pt/2009/01/20Aug2008004-1.jpg

Got it through Frank at GP. It's a quality unit. Here it is installed:

https://static1.pt-content.com/images/pt/2008/09/24Aug2008004-1.jpg

[Rhino]

I know it's not a popular choice around here.. but I'm building an explorer 8.8 for mine. Narrowing it to center the pumpkin and adding big ford ends to it.

Nice thing about the explorer rear is that it's 31 spline out of the factory. Most of them also come with a decent limited slip unit as well.

[Turbo67camaro]

12 bolts are about 3% more efficient and run cooler.

Ford 9 inch are much easier to swap gears.

More splines = thicker axles = less breakage = at a cost of more weight.

12 bolts w/ c-clip axles can be dangerous (flying axles).

I went with a custom 12 bolt w/ Truetrac diff. w/ 33 spline bolt-in Moser axles w/ 1350 yoke w/ Ford Torino housing ends w/ C6 Z51 brakes.

[ProdigyCustoms]

There are a couple aftermarket Posi available that are pretty tough, easy tough enough for that power.. You will have no problems.