I need to strengthen my my rear differential with my new combo. I don't want to run a spool, want to run a truetrac. Moser builds a 12 bolt rear end based on car specs for a 1970 Chevrolet Chevelle. Will this fit in my 1970 GS, without too much monkeying around? I need to step up on axle splines as well. Or, will 30 spline axles and a truetrack be enough in my 8.5 10 bolt? 656HP 605 TQ approximately 3,800-3,900 LBS Thanks.
Joe, What all will have to be modified, if anything to mount all the control arms, shocks, sway bar, and brake lines? Thank you for responding.
Nothing. The 70 Chevelle style rear is a direct bolt-in. The Moser housing has some modern geometry benefits. The upper ears are raised higher,similar to when you install a set of no-hop bars. It brings the instant center towards the back. They also moved the shock mounts directly behind the lower control arms,like a G-body,to take some angle off the shock,and let it react better. All of this helps with traction & 60-fts. You will need to check your driveshaft length,and possibly need a longer one. The 12-bolt has a slightly shorter snout,but there are some yokes available that have a little more reach forward. The Mark Williams style is more flat,and you would definitely need a longer shaft with that. If you are going to order a new Moser 12-bolt,go right to 33-spline. You can get a variety of units for that. You will also want to get it with the #7900 housing ends. These allow you to run a SET20 tapered bearing and have the same GM pattern for the backing plate. As for your 8.5",it can take that power. An 8.5",upgraded with 30-spline axles,and a good unit,com go well into the 9's. I've had one as fast as 9:20's,with a clutch-400(no converter),but at a lighter 3300lb car weight.
Putting a 12 bolt for a Chevelle under a GS is easier than putting a 455 in a 350 car. It is just like swapping any rear end, everything hooks up except the drive shaft. I think the 12 bolt drive shaft was shorter in my car because the 10 bolt with the same drive shaft and a conversion u-joint was a bit tighter to install.
