pontiac/olds rear end ID

i have either a 56 or 57 olds/pontiac rear end...

are there any numbers that will tell me the ratio on the rear?

57 is WAY better, and i think thats what it is.. but let me know...

any help is appreciated...


THANKS

 

56 and 57 should be visibly different.

The 1958 shop manual I have shows a code is stamped on the front of the carrier, on the outside edge, lower right side (passenger side). It should be adjacent one of the bolts. If you're really lucky, there may still be a color code on the end of the axle shaft, but unless the car's been stored indoors in a dry climate it's whole life odds of that are pretty slim. Get the code and post it and I can tell you what it is - even numbers are higher ratios.

The biggest visible difference I see in the two carriers is the 57-up has a top stiffening rib and the ribs (and the carrier housing itself) have a more pronounced hump to their shape; the 49-56 has 2 ribs on each side that have a plain arc to them and the housing.

The Motors diagram shows the rear cover on the '57-up to be raised on one side to clear the gear, while the '56 I had a while back I am pretty sure is smooth and round. The rear cover is part of the housing and not removable.

 

Codes for 1956 ratios as follows; Code 6 is 3.64:1, code 8 is 3.42:1, code 9 is 3.23:1 and code 0 is 3.08:1.
Hope this helps.

 

Those codes are the same for '57-up, so that won't help tell between '56 and '57.

'57 will have 29 spline axles, unless someone's been into it before, or unless it's a '59-up (which has 31 spline). '56 has 16 spline I think. And I think '53-back has 10 spline.

'57 pumpkin will be PERFECTLY round. '56 pumpkin will be slightly out of round.

 

the list above doesn't show a #2 for a code which my 63-4 has ,looks like I have to go into it I founs another post that says 2:76 for a #2 code, which just plain dos'nt seem right for a 63 2+2 Catalina

 

Years ago, I parted out several '61-'64 full size Pontiacs, and found really lame gears in most of them. Remember, the ones that came with a four speed hydramatic had such a steep low gear that they could get away with 2.69 or 2.56 in the rear. Only the stick shift cars usually had anything decent in them. The one exception to that was the pair of '62 GPs I parted out; both automatic cars, both 3.23 gears.

 

Found this post during search, can you help me ID this rear end? The PO said it was Olds.
Thanks.....

 

Housing is 53 7/8" flange-2-flange

 

also, his buddy CJ needs the torque specs fer the yolk nut.

 

Looks like '57-64 Olds/Pontiac. The pumpkin looks perfectly round and not oblong from the pic. The two ribs tells me that the pumpkin itself would be '57-8. Not sure about the housing. I don't see any perches.

BUT you PM'd me and said it has 16-spline axles. That would be '54-6 or so. Something's not right. Plus the yoke doesn't look to me like '57-64. Perhaps my computer screen is making the pumpkin look perfectly round when it's not??

Post some side views so I can see a side view of the rib that blends into the pinion part of the casting. Maybe I can tell from that.

 

I picked up a 57 poncho rear a little while ago that has the same yoke on it as the one pictured. I've never seen one like that myself..
The guy i got it from is a friend and told me they pulled it from the car themselves..I believed they knew the difference between a 57 pontiac and olds ..but if that one if from an old's maybe mine is as well..
I'm stumped too.. when i go to use this thing i'm going to have to figure out what to use as a yoke.

 

Not sure about years but GM used u-joints with caps that match that flat style flange.

 

I have a Chev. rear end that is a 4 bolt axle. I pulled the rear cover and the ring gear shows 15-38. I can't find this combination listed anywhere. That would be a 2.53. . I think it is a 8.5 10 bolt. Maybe out of a Vega? Any ideas appreciated.

 

Should be in this thread...
http://www.jalopyjournal.com/forum/showthread.php?t=129676

 

The rear end in post 7 is a 56-earlier rear. It should have 10 spline axles.

The larger 57-64 rear was actually available in later 56 models due to Nascar and the dual quad engine. Here's the best pic I can come up with for now, look at how round the carrier is.

 

Is the 58 Olds the best of them?

 

Rckt98 spells it out right. I have two 0 code 3.08's and a 9 code 3.23. Even turned the wheel and counted the revolutions to make sure. In spite of the spline count, the mid fifties Olds rears were known to hold up good for 1/4 mile. That's why I didn't even think about swaping out for a later rear in either one of the 55 Oldsmobiles I have.

 

I just bought a '55 olds rear end for my coupe yesterday and also have a related quick question.

The rear end came out of a '55 olds 88. I was told the rear end gears are 3.25 gears. I am ok with this setup for the coupe, but my question was in the yoke!

It is the flat type. Does anyone know the yoke spline count, and what yoke would fit that rear end for a gm driveshaft? Will a '57-'62+ b.o.p yoke work?

I saved the driveshaft from the '62 and it has the regular u-joint setup just in case. I'm a newbie when it comes to oldsmobile rear ends. Any info would help.

 

The driveshaft that came with the 55 itself has a regular type end on it , half the u joint cups are round the other have a flat flange. You need to get the rear u joint for that rear. This ain't the best pic but here's what you need. It would probably be easier to find a doner driveshaft for the end than trying to find a yolk that works, I don't think anything else will work.

 

Thank you for the great info and picture!

I know the oldsmobile was a pretty stout car for the early days, but do you think the stock '55 olds driveshaft/differential setup will hold up?

I'm building a '30 A coupe with a hopped up 394 olds with a muncie 4 speed. I just don't want a failure to occur on a road trip or at the dragstrip. I am so used to using rear differentials from the 60's with 28/9 - 31 spline axles instead of an oldsmobile 10 spline.

 

Manual trans cars are always harder on parts, especially with slicks. You may be better of with a 57-64 rear with 29/31 spline . Also there is no posi unit for this early 10 spline rear.

 

That is awesome! I just checked out the schucks website. Just found out that there is quite a few parts for '57-'64 Olds / Pontiac rear differentials. There really ain't much for the early olds.

I know you can also get parts from Kanter Auto Products.

Thank you 55chieftain and everyone who has posted to this for all of the good information!


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Don't beat the crap outta it and it will hold up fine...

 

Great info on these rearends! There is also a new center section in both nodular iron and Aluminum alloy coming out for these rearends. They have been redesigned to be able to go up to racing 40 and 44 spline axles instead of the limited to 35 spline currently.

 

postin so I can find later.

 

Good way to keep track of a great info thread!

 

Hey, I'm at a loss, after reading all these posts, I still can't find anything on my
" Olds Rearend " The numbers on the pumpkin, passenger side dowm low are
E-219 Then under those I have 534548 as near as I can tell. Also it's an open rear end ? Why would they do that
Any help would be greatly appreciated.
Thank God for spell check.

 

The top set of numbers are date codes, I'd guess 6/21/59. Maybe 49, I don't know what a 49 rearend looks like.
Larry T

 

If I can load one up I'll send you a pic. but I'm getting a sick feeling. Will a later model posi unit fit in there if it's that early a rear ??

 

No, the '57-'64 style posi unit will not work in the earlier rear end.