8.5" 10 bolt or 12 bolt or 9"

[Bad94]

Im going to be doing the Quadralink in my project and i have a 8.5" 10 bolt now with a eaton posi. Not sure if i just want to step up to a 12 bolt or 9" now. I dont want to build the car now and then have to redo the rear end a few year down the road.

I plan on doing a LS based motor, with about 450-500 RWHP.

[big gear head]

The 8.5 can be built to handle that if you want. The 12 bolt is nice, but more money. It can easily handle that amount of power. The 9 inch is too much for what you want, but that's my opinion. The 12 bolt and 8.5 are lighter and take less power to turn. The 9 inch is also more expensive to build.

[Scott Parkhurst]

I'm a big fan of the 9-inch because it's overkill. Should i choose to up the power level in the future, the rear axle is ready for it. Parts are easy to get. Lots of brake kits available, too.

Plus, I can swap out center sections and gear ratios easily, which is cool if you run different kinds of events. I have a street/road race center section (TruTrac w/ 3.89s) and a drag race center section (Detroit Locker w/ 4.30s) to cover my varied interests. Its about a 30-45 min swap.

No 8.5 or 12-bolt can do that for ya.

Guess how much time I've spent worrying about my rear axle since I installed it? None. I like that kind of confidence.

[PhillipM]

A good friend of mine is running an 8.5" 10. Has been since the car was new in 74. Today he is putting down over 600 hp on it with a 9" MT slick. To date has just put good parts in it and left it alone. Has he blown posi's up? Sure, but every rear will do that if you are being a jack ass with it. I would stick with the 8.5 if you already have it and spend the money somewhere else. Just be sure it has good parts in it.

On another note, another friend of mine had a 66 Chevy II with a 9" in it. He broke stuff all the time and always replace the parts with junk low dollar units. So, just becuase it's a 9" doesn't mean it will take anything you can give it.

[MarkM66]

A 12 bolt or 9" will ad more value to the car then a 10 bolt, if resale value is ever going to be a concern.

[Nothingface5384]

i'd do a 71-72 8.5 10-bolt from a skylark or cuttlass due to it being the strongest style(bolt-in axleshafts) 8.5 and then just upgrade to 30 spline chromoly axles
but if you;re not looking to search then weld, but if they have a 12bolt readt houseing then just get tyat and use bolt in ends from a 9in or something

[ProdigyCustoms]

I would do a 12 bolt. A 12 bolt will easily handle the power. Mark is dead on, the car "needs" a 12 bolt if for no other reason then future value. The 10 bolt will be a real limp noodle when writing the ad for this car some day.

To install the Quadralink brackets, the axle end have to be cut off so the brackets can slide over the tub. So if your lusing a stock 12 bolt, this is a great time to change the ends to big Fors ends.

Or we can do a brand new 12 bolt and jig weld your Quadralink brackets BTW