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Old 12-08-2008, 07:50 PM
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Swapping '73-'77 A-body rear end into a '71, & related questions?

I just spent an hour or so searching to see if my questions have been answered. No joy.

I have a '71 El Camino with a TH350 tranny and a 8.2" 10 bolt. I'll be swapping in a blown 355. I can build up the tranny, but I want a stronger but still cost effective rear end. I can't see spending over $2K for a Ford 9". It's not a race car. It's a street car that's never seen a track, and even with the Weiand blower it won't make over 500 horses. But it will have about 500lb/ft of Torque, and I'd like to be able to take it to a track occasionally. Basically, I want to be able to drive the thing without worrying the rear end is going to shatter like glass if I don't baby it. I'd rather find something that can bolt right in (after an overhaul; these are all 30 year old components) before I start considering parts that'll need to be modified to fit. Or go the more expensive aftermarket route.

Unfortunately, I'm having a hard time finding a stronger bolt-in rear end. The easiest and most cost effective would be to swap in a correct 8.5" 10 bolt. But I've had no luck finding one. Chevy may have started using 8.5" 10 bolts starting in '70 for Camaros, but from what I'm finding locally it seems that they mostly kept using the 8.2" rear end through '72 in the A-body.

So '71 & '72 8.5" rear ends I can't find. But later mid-'70s 8.5" 10 bolts I can. I'm hoping this is something close to a bolt-in rear end. Did Chevy make a lot of extensive changes when it redesigned the A-body in '73? What's involved in swapping a '73-'77 A-body rear end into a '71?

12 bolts are very rare and very expensive. If I do find a '68-'72 A-body 12 bolt, what's a fair price for what's basically a rebuildable core?

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Old 12-10-2008, 09:23 AM
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I think the mid 70's A-body rears are wider, the lower control arm mounts are in the same location but the upper mounts are different. 12-Bolt open rears are still fairly cheap, then buy a Posi, gears & axles for strength. Thats what I did, got a Yukon Posi, Gears, Axles, Solid Pinion Spacer,Master Install kit & Rebuild Video for $825 Shipped at http://completeoffroad.com/

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Old 12-10-2008, 11:15 AM
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Originally Posted by SSedan64
12-Bolt open rears are still fairly cheap,
Maybe where you are, but here in the mid-Atlantic area even bare 12 bolt housings for an A-body are going for stupid money. By the way, do NOT confuse the 67-70 Type O axle with a real Chevy 12 bolt. The Type O was used under Cutlass and 442s only, and despite having 12 bolts on the cover, it only has a 10 bolt ring gear.
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Old 12-14-2008, 01:40 PM
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1973 10 bolt

I will measure up the diff in my 1970 Skylark and tomorrow I will measure the 10 bolt in a 1973 Cutlass I just got and post the numbers then.
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