[Gloryhound]

I got an axle housing at a swap meet. It has measurements that make it a Nova rear and it looks like an 8.5" 10 bolt. I can't find the numbers to match up on the Nova resource page, so I thought I would see if someone here can help.

Here are the numbers:
7 FC 0 259 on the passenger side axle tube
555771 on the center housing with an F and 254

Thanks for any help!

 

[Philip]

Could the FC be a poorly stamped PC? That would make it a 4th gen 8.5" 10 bolt. All of them were 3.08 gears. Have you had the cover off yet?
As long as the width is correct and it is an 8.5" it should be a keeper.

 

[Philip]

I just checked Scotts page and it might be an Olds rear from the numbers you posted. But the 7 FC would have to be a 2 PC.
2PC = 3.08 open
O = Oldsmobile
259 = day of the year it was built
FWIW the 3.08 open rear in my 75 was not listed at Nova Resource.

 

[CDJr]

While were on the subject........lol. I cant find the info for the rear that came in my 74 Nova either. Im pretty sure itd been changed before I bought it though. The code was GB G262 1. If you can find that one for me Philip, Id surely appreciate it

 

[Philip]

The second G indicates it was built by Detroit Gear and Axle. The only ratio G codes listed are for a 71 with 8.2". Is yours an 8.2 or 8.5?
I need to go get the casting numbers and stamped numbers off of the three 8.5" units I have and see if it will shed some light on ID's, they range in years from 75 - 79.

 

[Gloryhound]

I'm pretty sure the code I pulled is correct! The housing has all four little ears like the 8.5" housing, 10 bolts in the cover, and the pinion is 1 1/4" nut. I haven't had a chance to open it up yet and see if I can get numbers off the carrier, but if I get time tonight I might do it.

I have to agree with you Philip in that how I read decoded it it came up as an Olds rear. Probably it actually came out of an Apollo. I'm not sure but it could be due to the lack of Apollos I've seen the Oldsmobile data on the Nova page could be incomplete. I see alot of Ventura, but not many Apollo or Omega's!

 

[CDJr]

Mines an 8.5", and I couldnt find any info on it either. Im assuming its a 3.08 open rear though.

 

[Philip]

I am poking around some Olds sites right now to see what comes up.

 

[Big Dave]

Can not be an O Olds rear end because the Olds ten bolt rear end has twelve bolts holding on the cover. It doesn't use "C" clips (which is why the Chevy rear is known as a C rear end) so the axles are bolted to the rear end just like Ford rear ends. And lastly they only made them for three years so they are rare as hens teeth.

The ten bolt Olds has an 8.3" diameter ring gear unlike the C rear end which was either 8.2" in diameter or 8.5". It has two carriers an open three series with two spider gears in an open rear, or a four spider gear that uses an Auburn gear cone style limited slip rear end with 3.90 and up ring gears (only available in the Cutlass 4-4-2 package which has ears on the pumkin and no leaf spring perches).
There are also two sets of rear axle bearings for the same rear end as the originals failed under warranty and were recalled, and replaced with the "new" bearing design.

I guessing he has an 8.2" ten bolt out of a Camaro or Firebird.


Big Dave

 

[Philip]

Can you post a photo of the rear? or send me one and I'll post it for you. The 1 1/4" nut makes me beleive you do have an 8.5" not an 8.2"

 

[Gloryhound]

I started looking a little harder and now it looks like it is a 7.5" 10-bolt out of a 78-79 Nova. I have pictures but can't upload them. I have the ID numbers and the rear of the housing itself. Not what I wanted, but it was only 15 bucks so I should be able to recoupe it even if I haul it in for scrap. Are the axles between the 7.5 and the 8.5 interchangable?

 

[Big Dave]

Yes, all ten bolt axels interchange.

 

[Philip]

Email me a photo and I'll tell you what you have. I am not sure if the axles will interchange. Some had 27 splines, some 28 and some 30. Best way to know is pull one of each and compare.

 

[Big Dave]

All car 10 bolt axles are 28 spline from '64 up until '89 when the 8.5" rear end went away and was replaced by the 7.5" rear which has a 30 spline axle; so I am wrong in that regard (they also have an ASB reluctor attached which render them useless). The 8.5" ten bolt rear continued in production in trucks (used a different posi which isn't recommended for cars), but the axles are 30 spline and are too long for the Nova/Camaro rear end (they often have six lug axle flanges as a dead give away that they won't fit).

You can buy a 30 spline axle for the ten bolt but; surprise, it's just a 12 bolt axle with the "C" clip end ground down 0.035". That is all you have to do to use a 12 bolt axle in a ten bolt (aside from getting 30 spline spur gears that come in the HD Eaton posi for ten bolt rears). To my knowledge they never made a Spicer rear end with a 27 spline count, but I could be wrong. I was a few seconds ago; sorry for the confusion.


Big Dave

 

[Gloryhound]

Phil,
I sent you the photo's, but I'm pretty sure looking at the rear cover that it is a 7.5" housing.

Thanks

 

[Philip]

Got them and it is a 7.5"

 

[big gear head]

The 7.5 was used in the Nova and other X body cars starting in '76 in the 6 cylinder cars. The 7.5 10 bolt has 26 spline axles up to '90, when it got 28 spline axles in the Camaro, Firebird and S series trucks. The 26 spline 7.5 axles will not fit in the 8.5 10 bolt, which has 28 spline axles in the cars (except the '90 and later Caprice and Impala, which had 30 spline axles). The 7.5 and 8.5 both have a 1 1/4 pinion nut, but the 8.2 has a 1 1/8 pinion nut. The "O" axle was not used in the Olds Omega. It has the 8.5 corporate 10 bolt.

 

[Gloryhound]

Well now I have to find a good 8.5" housing. I have an 8.2 and this 7.5, but both of those are open carrier. I have a posi 8.5 carrier, brand new ring and pinion for an 8.5 carrier, and a brand new installation kit for a carrier in an 8.5 housing. I should be able to use the axles out of the 8.2 housing since it has the same 28 splines as an 8.5 and be the proper length for a Nova. Guess I'll be calling the salvage yards tomorrow!