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Old 11-19-2002, 02:35 PM
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Post 77 Nova rear end compatibilty?

I need to know what rear ends will interchange with my 77 Nova without modification? Lookin for a possi unit with a lower gear. Appreciate any help.

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Old 11-19-2002, 02:43 PM
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Any camaro from '67 to '69 or any nova from '67 and up. This year range came with either 8.2, 8.5, or 7.5 ring gear sizes. 8.5 would be the most desireable. Switching from one ring gear size to the other may require a different length driveshaft even though the overall width and spring perch locations remain the same.

[ November 19, 2002: Message edited by: Jason ]</p>
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Old 11-19-2002, 04:57 PM
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I looked in my service manual for 78 chevy cars and it looks like you are able to use a F-body's (Camero/Firebird) on an X-body (Nova) or vise versa. The only problem as far as I can tell is that the shock absorbers may not line up exactly. The way to tell what axle you have is to look at the stamped code. It is located on the axle tube, passenger side facing the front of the car. It will look something like this:

2 HK G 8 218 1

Look where the letter 'G' is.

The letters 'G', 'C', or 'W' in that spot means it is a chevy rear. 'B' is Buick, 'O' is Olds, 'M' is Canada, 'P' is Pontiac.

Also note that the Buick and 'G' code Chevy have a 8.5". The Pontiacs have 8.75".

Now, if you look at the housing cover, you will notice the 10-bolt pattern. Another way to identify your rear is by the inspection cover. As you look from the back of your car to the differential, note the shape of the cover. If the cover is perfecly round, you have a 7.5" (codes 'C', 'O', 'P'). If the cover has two indents, one on each side, where the axles tubes connect, then you either have a 'B', 8.5" or 'P', 8.75". And if your cover has two small indents next to each axle tube, looking a lot like two half-circles that are not the same size placed next to each other, top and bottom, it is a 'G' code, the 8.5" chevy.

Unfortunately, there is no way to tell what ratio or whether it has limited slip without opening the case, if the factory aluminum tags are missing.

I hope this clears some things up. The Camero looks like the easiest donor, but it appears as though you could use any of the rears from 77 or 78.

[ November 19, 2002: Message edited by: 78novaman ]</p>
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Old 11-19-2002, 05:14 PM
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I'm not so sure of that info novaman, I have installed a 1979 camaro rear into a 1975 nova, the spring mounts didn't line up and the rear was about 1 1/2" wider. I ended up cutting and rewelding the mounts.
Also GM never put aluminum tags on these rears, there is a stamped code on the front of one of the axle tubes, for example PA is what my car had which means 3.08 open diff. I have seen the same code on both 8.2 and 8.5 rears. The code is only good if the rear has the original gears.
Also a 7.5 rear cover is slightly oval. 8.2 and 8.5's are perfectly round. The 8.2 usually has a crease accross the cover.

[ November 19, 2002: Message edited by: Jason ]</p>
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Old 11-19-2002, 05:36 PM
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Cool

first, I said 77 or 78. I did not say any model to any other model. The 75's were WAY different (whole different body style for the nova), I am not sure about the 79 camero.


As for the info, it was pulled strait from my 1978 Chevrolet Service Manual. I even went outside and confirmed it with my own car. Close to all of it should pertain to 76-79 GM passenger cars.
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Old 11-19-2002, 05:39 PM
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Angry

By the way, when I said round, I ment no indentations, the 7.5" is indeed oval.
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Old 11-19-2002, 10:02 PM
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[quote]Originally posted by 78novaman:
<strong>first, I said 77 or 78. I did not say any model to any other model. The 75's were WAY different (whole different body style for the nova), I am not sure about the 79 camero.


As for the info, it was pulled strait from my 1978 Chevrolet Service Manual. I even went outside and confirmed it with my own car. Close to all of it should pertain to 76-79 GM passenger cars.</strong><hr></blockquote>

No all '75 and up nova's have the same body style. The only difference I see is that you are pulling info out of a book and I and am getting info from actual experience. Just trying to help the guy who asked the orignal question. Look at this 1975 nova...is it the same as 1976 and up???
Sure looks like it to me...

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Old 11-20-2002, 01:59 PM
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Cool

Oops, I goofed. Good catch though! The last generation of the "real" Nova's did indeed start in 75. Sorry about that, I had my dates messed up.

Were the 2 axles different lengths too, or were just the mountings different? I knew that they used different shock mounts, but I figured they were in the same place, and that all the 10-bolts (of the 77 and 78 years) were the same width.

One thing I would like to know though, how much wider is a 12-bolt out of a 1974 C20 going to be than my 10-bolt? Will it even fit in my Nova? I was thinking of upgrading my rear when I get a V8, since I have the baby 7.5".
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Old 11-20-2002, 07:57 PM
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The spring mounts were in different locations and the width from axle flange to axle flange was wider. The shock mounts are actually not part of the rear, they are the bracket that goes under the spring. The mount welded to the axle tube and the shock mounting bracket are what clamps the leaf springs onto the rear. The brackets do interchange but like you said the shock mount end is different.
I had a 12 bolt out of a 1972 c-10 (I think) van, it was way wider than the nova rear but it can be made to work by narrowing it.
One interesting option I've been considering is an 8.8 ford rear out of an explorer. I had a '92 ford rear with factory 3.73 limited slip and 31 spline axles. It measures 59 inches from axle flange to axle flange and are available with disc brakes. That would be an upgrade in axle size even if it replaced an 8.5, and the narrower width would allow wider tires.
I have the 28 spline ford ranger 8.8 in my S-10. It was a pretty easy swap as far as cutting brackets off and re-welding them in new locations. These rears use a companion flange to mount the driveshaft to the rear (instead of u bolts or straps) the stock nova u joints fit right into these.
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Old 05-03-2006, 09:08 PM
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12 bolts

I have a 79 nova with a 12 bolt out of a 69 camero dz car. the rear end bolted up with no problems it is about 1.25" wider than the 7.5 10 bolt that was under the car stock. the only thing that was different was the u-joint was special for a12 bolt on one side and a 7.5 10 bolt on the other. I hope that was a little help C.P.

Last edited by cwptaz; 05-06-2006 at 04:31 AM. Reason: more info
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Old 05-03-2006, 10:26 PM
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Which rear end does yours have? 1977 V-8 cars would have had the 8.5", but 6-cylinder cars generally got the 7.5". Watch out for a length (not width) difference between the 7.5" & 8.5" rear ends. The 8.5 is a little longer from axle centerline to U-joint centerline. It may cause your driveshaft not to fit.

Also, '77s had multi-leaf springs, which were found on '72 SS cars, and all Novas from '73 up.

Here's an ID site if you're not sure: http://tech.oldsgmail.com/axle_ident.html
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Old 05-04-2006, 06:01 AM
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Quote:
Originally Posted by 78novaman
I The way to tell what axle you have is to look at the stamped code. It is located on the axle tube, passenger side facing the front of the car. It will look something like this:

2 HK G 8 218 1


Unfortunately, there is no way to tell what ratio or whether it has limited slip without opening the case, if the factory aluminum tags are missing.
Your last statement couldn't be more wrong, so please don't take offense but I'll prove my point.
That stamping you mentioned shows this information:
2HK=Ratio (I didn't look hard enough to find this code.)
G=Plant (Detroit Gear and Axle assembly plant)
Day of Year, should read 001 through 365, your code doesn't pan out with information found on the internet.
Shift code should be next and will be either "D", or "1" for day shift, and "N", or "2" for night shift.
Posi Source would be next if the axle was originally equipped with a positraction differential.

This information is for 1971 and later GM axles, 70 and earlier are different.
Axle information.
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Old 05-08-2006, 05:13 PM
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Holy resurrection of an old thread batman!

That must of been like my 3rd post here lol!

Boy I sounded really dumb back then....and I can't believe I wrote that!


Thanks for fixing it M&M, I must have thought I knew everything back then.
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