# Needing help another weird rear end ID.



## benw88 (Jun 28, 2015)

Hi. I have a rear end that I was told came out of a 70’ GTO, but I haven't been able to ID it with the codes I have .The code is SDB 014 -1 on the axel tube. None of the Pontiac ID’s that I have found match up. Do you know of another source that can find this code? Thanks


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## Pinion head (Jan 3, 2015)

the rear is not a Pontiac 8.2 10 bolt used in a Pontiac LeMans or GTO. The rear is an 8.5 A-body. Which style, I can only narrow down by eliminating 3 of the possible 7 different styles as someone has whacked off the lower control arm/shock mounts.

Looking at one of the axle flanges, how many access holes in the axle flange, 3 or 4?


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## 05GTO (Oct 6, 2004)

benw88,

SD = axle ratio and year
B= Buick
014 = Julian Date, January 14
1 = Day Shift 

This is the coding scheme for 1971 and later and I can't find the SD code which would give you the year and ratio. It appears to be a b-body rear end.


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## 05GTO (Oct 6, 2004)

After a little more research I found the SD code was used from 1968 thru 1972 and the gear ratio was 3.08:1.

here are some images showing the differences between the BOP rear ends;


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## Pinion head (Jan 3, 2015)

The rear is not a '68-70 BUICK A body rear, those are '68-70 BUICK 8.2 10 bolts. The 68-70 BUICK 10 bolt differentials only went under Buick A-bodys originally. The '68-72 BUICK 10 bolt was introduced at a time where engine torque levels had increased and the previous gray iron '64-67 Buick cast 8.2's were not holding up under heavy thrashing. 

-The '68-70 BUICK 10 bolt had its own specific cast center section, that specific center section is easily ID'ed, as it has one recess for a plug weld on each side next to the rear cover, not two.
-The 68-70 BUICK 8.2 hsg is cast and machined to take the larger 12 bolt carrier bearing race under the LH carrier bearing cap, the RH (pass) side take the normal small diam 10 bolt bearing race, this requires the '68-70 BUICK 8.2 10 Bolt to have its own style carrier, and it also had its own ring and pinions. The axles, though 28 spline and same length as late '66-69 Pontiac 8.2, axles, will not mesh with the Pontiac 8.2 side gears, as the splines are different. So much for the rear being a a '68-70 Buick 10 bolt.

If the rear was a '71 or 72 usage Buick built 8.5 Abody rear, I would expect it to have one plug weld recess per side next to a round rear cover. The particular 8.5 A body rear in the OP's picture has two plug welds per side and also has the large square lugs on the bottom of the housing...both note this early corporate rear was cast by Olds axle plant. this style rear besides going under Cutlasses and 442's was installed in Buick Skylarks and GS's. The vast majority are 2.73 singletracks.

As cannot easily determine the spread between the cast upper control arm perches, could not tell easily from the pic if the hsg is a '71-72 or a '73-77 style A-body housing. Each style are easy to spot when the outer lwr control arm brackets are still welded on. If you look at the axle flanges, other than the 5 axle studs, there will be 4 larger holes in the ends of a bolt-in axle '73-77 A body rear. The most common '71-72 8.5 A-body housing's mating axle has only 3 access holes in the axle flange. It also uses the cutout style rear cover with two plug welds next to each side of the rear cover. Another way to quickly tell the difference is take a tape measure, the '71-72 8.5 A body rear will measure 55.25" from the flange where the backing plate mounts on to the opposite flange area. The '73-77 style are a hair over 1" wider. 

Have nearly 3 dozen cores of all these housings either in my hsg racks or on the scrap trailer. Began to build up the bolt-in axle 8.5 A body rear for performance use in the early 90's, just in bolt-in axle 8.5 A body rears, have built over 300 for performance use.


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## Pinion head (Jan 3, 2015)

05GTO said:


> After a little more research I found the SD code was used from 1968 thru 1972 and the gear ration was 3.08:1.
> 
> here are some images showing the differences between the BOP rear ends;


This illustration is mainly good for noting the earliest Pontiac 8.2 10 bolts and earliest Buick cast (single rib) 8.2 10 bolts. Most longtime GM differential builders don't use the term B-O-P. It is a misnomer. There were early weak gray iron Buick 8.2 10 bolts, type "O" Olds 10 bolts, the '68-70 BUICK 10 bolts, and a whole spectrum of 8.2 Pontiac 10 bolts. Very little internal interchange of parts between the 4 style rearends, but one will still read silliness like "rearend is '67-72 B-O-P" or "ring and pinion fits '64-72 B-O-P"...not!

Oldsmobile did not cast their own 8.2 10 bolt center hsgs on 10 bolts used under their own early A-bodys. Instead, Olds sourced 8.2 housings from Buick, and eventually Pontiac's for the '64-66 modell years. The twin parallel rib style housing was first introduced in a 10 bolt by Oldsmobile in their own new for '67 type "O" Olds 10 bolt. These had a 10 bolt 8.3" diameter ring gear with a smooth 12 bolt rear cover, many Olds guys will call this rear a 12 bolt, but it is not. The type "O" Olds 10 bolt continued to be installed through the 70 model year under Cutlass and 442's, the strongest are 31 spline axle '68 Anti-spin units.

Throw all this out, as the illustration was originally noted in Hollander interchange manuals, and has made it into multiple magazine articles over the years and for the last generation, internet sites, and is no where near factual. Hollander actually had a very rough time keeping track of all the different GM Salisbury style rearend pieces under '64-72 GM A body's, even not noting certain axles in their manuals.


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## 05GTO (Oct 6, 2004)

Pinion head said:


> The rear is not a '68-70 BUICK A body rear, those are '68-70 BUICK 8.2 10 bolts.


I never said the OP's rear end was a 68-70, I said the SD code was used from 1968 thru 1972 and the gear ratio was 3.08:1, 

I, also stated "This is the coding scheme for 1971 and later"


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## Pinion head (Jan 3, 2015)

05GTO said:


> I never said the OP's rear end was a 68-70, I said the SD code was used from 1968 thru 1972 and the gear ratio was 3.08:1,
> 
> I, also stated "This is the coding scheme for 1971 and later"


I Id'ed the rear by specific features of the housing. Have all 3 styles of '71-72 8.5 A body rears in the racks. Have a 41st and 47th Hollander 5 feet away and didnt waste the time to search through division wide axle stamping codes. Here's why, if you examined enough GM rears of this era, you would not be so eager to ID by stamped code. The stamped codes aren't always right and some are unknown, or very hard to nail down (like all the McKinnon stamped codes for the '68 and '69 12 bolts installed in Canadian built Olds and Buick A body's). Many other rears the stamped axle tube codes are rust pitted or weld spattered. One of the rears in my racks is a 3.91 Anti Spin out of a '68 Olds RamRod, it had some odd brackets welded to it. The weld spatter obliterated part of the code. Also have a '68 nodular casting number Pontiac 8.2 out of a GTO, it was most likely a 3.55 Safe-T-Track, but was later assembled with 4.33 gears, and the 4 pinion STT carrier, and then the axle tube was stamped with the code for a '69 4.33 HD STT. The old friend who professionally assembled it, put in his 428 RA5 headed '69 Judge. Just looking at the ID code and googling, any average car guy would think it is an original Pontiac 4.33 HD STT rear...it's not, does not have the correct nodular casting number. Have run across multiple dozens of similar deals, that's why when I viewed the pictures I noted exactly how to ID the rear. 

Anyone can put a stamped code in a Google search bar. The info retrieved is only as good as the quality of the info being inputted to the original book or website. Google any of the large GTO information sites like GTO Heaven, they all have regurgitated lists often filled with errors. Even John Wallace's site, which is often used as a reference, has many errors. Years ago, I sent a quick email to the owner of GTO Heaven site, noting that there were no Pontiac A body's built out of Arlington or Baltimore assembly plants for the '71 model, his info stating that GTO's were being out of these plants for '71 was erroneous. The info I noted is documented by production totals from the plants, his was gleaned from several pages in the front of a Year One catalogue.  Heres another: The Oldsmobility website has pictures of an 8.5 A body center housing up on its website. On at least two dozen times have read website posters note that website link and state that "a '71-72 8.5 A body rear will have the square lugs under the bottom, that's how you identify them". Well that's not totally true, there are two other styles of that particular configuration rear that never had the square transfer lugs on the bottom of the housing.


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## jacaranda_ser (Aug 15, 2019)

To Pinion Head, if still monitoring this site:

I pulled a rear axle from a 71 LeMans that appears to be similar to the OP's rear end. It has a 1.25" pinion nut, but it doesn't have the big squared off lugs/protrusions at the bottom of the housing. It does have a similar cover and has two plug-weld access holes per side. I have not been able to find the codes stamped into the axle tube and will have to wire brush the area to remove the paint. Is there any positive means for identifying that this is an 8.5" unit from the outside. I haven't opened the cover yet, but it has a limited slip tag attached. The axle may not be original to the LeMans, since the prior owner was building a Judge clone and had bolted on many non-original parts. I was planning on using this on my 72 LeMans, but only if it is an 8.5" unit.

Thanks.


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