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Discussion Starter #1
I'm sure this has been covered, but there is no search or at least I didn't see one. So here's my questions...

Which rear end is easier to find parts for??
Which rear end is stronger??
What will fit under my 68 Nova, meaning: What years are compatible, and what rear ends from other types of cars will work??
Which is stronger 10 bolt or 12 bolt??
Better 8.2 or 8.5??

Final question subject:
Ford 9 inch...
What is needed to be done to put a Ford 9 inch in my 68??
Are these rear ends stronger then the others??

I'm going to a Swap meet here in Houston this weekend, and need to gain some knowledge on rear ends... I know there's allot of great knowledge here!!

Thank a million,
Bryan
 

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OK, a 8.2" 10-bolt isn't made of glass but it's not the strongest rear you can get. Yes, a 12-bolt is stronger but they are not cheap. A quality 8.5" 10-bolt is 99% as good as a 12-bolt (in my opinion) and much cheaper. 8.5" 10-bolts are found in every 1972-75 GM X-body and most 1976-79 X-bodys. Be careful checking 1976-79 X-bodys because they could have a weak 7.5" 10-bolt

Ford 9" are also not cheap and are more image than anything (again, in my opinion). Yes, they are strong but they also absorb more HP than a 12-bolt or 10-bolt.
 

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Discussion Starter #3
The terms 8.2" & 8.5", refers to the ring gear size, measuring the high of the gear... right?

...and 10 bolt & 12 Bolt, refers to the number of bolts that hold the ring gear on.

The strength comes from not only 2 more bolts holding it on, but also the fact that the bolts are different size... correct??

I took a rear end out of a 74 nova with a 305/350 setup... What would you guess that would be??

Thanks
 

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I took a rear end out of a 74 nova with a 305/350 setup... What would you guess that would be??
My guess would be someone did a motor swap, and it has an 8.5" ten bolt.
 

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68Nova2 said:
The terms 8.2" & 8.5", refers to the ring gear size, measuring the high of the gear... right?
Diameter.

...and 10 bolt & 12 Bolt, refers to the number of bolts that hold the ring gear on.
Correct

The strength comes from not only 2 more bolts holding it on, but also the fact that the bolts are different size... correct??
It's not the really the bolts, it's the size of the ring rear (12-bolt is 8.875" in diameter), the size of the pinion bearings (8.5" 10-bolt and 12-bolt are the same; 8.2" 10-bolt is smaller) and the size of the axles (12-bolt = 30 splines; 8.5" 10-bolt = 28 splines).

I took a rear end out of a 74 nova with a 305/350 setup... What would you guess that would be??
Unless it was changes by a previous owner it has to be an 8.5" 10-bolt. ALL 1972-75 came only with the 8.5" 10-bolt from the factory.
 

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Discussion Starter #6
Very good information... I thank the both of you... Thanks!!

OK, I know the rear end is original, but the 305 wasn't... not sure what was in there before.

So, I have a 8.5" 10 bolt... gears???? I have no idea, don't really care.

I want a POSI with 373 gears!!!

So, can I get a POSI unit that fits a Chevy 72-75, 8.5" 10 bolt, and put it in??

Then for the gears, I would need to buy a kit to get all the spacers etc.??

Am I moving in the right direction? Thanks.
 

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Here is what I picked up from Summit for my '73:
Eaton Posi $399.88
3.73 Ring & Pinion $169.88
Install kit $128.95

You may be able to find the stuff cheaper in a salvage yard or another supplier, but this is the ball park figure.

Luke

P.S. Don't forget labor, unless you feel like taking istall on yourself.
 

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luke'snova said:
Here is what I picked up from Summit for my '73:
Eaton Posi $399.88
3.73 Ring & Pinion $169.88
Install kit $128.95

You may be able to find the stuff cheaper in a salvage yard or another supplier, but this is the ball park figure.

Luke

P.S. Don't forget labor, unless you feel like taking istall on yourself.
Luke I'm looking at doing a rear end as well same set up essentially as what you list above. Did you have it done? What is labor generally on a 8.5 rear-end rebuild with parts listed above?
 

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I sometimes wish i had found an 8.5 10 bolt for my car but since i didnt i just went with a moser 9", i spent a little more money than a 10 bolt, but changing gears are a snap, plus i have alot of race buddies that use 9" stuff which helps the pocket book when i need stuff
 

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NovaNate said:
Luke I'm looking at doing a rear end as well same set up essentially as what you list above. Did you have it done? What is labor generally on a 8.5 rear-end rebuild with parts listed above?
Actually, I was planning on the swap myself, so I haven't priced the labor. The only exotic tools needed (according to everything I've read) are a dial indicator for checking run-out (bought when I degreed my cam) and an in-lb torque wrench.

Luke
 

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If you buy a new posi get the one with 30 spline side gears, that along with 30 spline axles will make your 8.5 as strong as a 12 bolt. Stock 8.5 nova diffs are 28 spline.

Mike
 

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Check out this online outfit, Power Train truck and auto parts, I did posi carrier, ring and pinion, install kit, axle bearings and seals, shipping under $650.
Paul
 
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