Hi Folks,

Winter is back, so time for some shop time! Question is this, what rearend/axle housing should an original 1970 442 have under it? IE. was the 12 bolt an option, leaving a 10 bolt as standard? Want to make sure I restore the proper type to put back under the car.

Thanks in advance!

 

Assuming your car was produced in the US, your car should have a Type O differential. This differential will have 12 bolts on the inspection cover but it is really a 10 bolt because there are 10 bolts that are used to attach the ring gear to the carrier. People who are not familiar with this differential commonly refer to this rear as a 12 bolt but it isn't. The other thing with this differential is that the axles bolt into the axle tube ends unlike a typical "Chevy" rear which uses C clips on the axle ends inside the carrier to retain the axles. As far as gear ratio's you could have had several different ratios and the code for the ratio used would be stamped on one of the axle tubes. Looks up a active thread here on CO by ALLAN R titled "Gassed, Another MAW Disaster" and you will see the Type O differential that he restored for his 72 Olds.
Brian

 

Every single Cutlass/442 built in 1970 had the 12-bolt O-axle. It has a 12-bolt cover,and a 10-bolt ring gear.Parts to these rears are unique to themselves,meaning parts from another type of rear do not interchange.These rears were made from 67-70.
The correct codes and ratios for 1970 are as follows:
R3 = 2:56 posi
SB = 2:78 posi
SD = 3:08 posi
SF = 3:23 posi
SH = 3:42 posi
SJ = 3:91 posi
TM = 3:42 posi (W31,W30)
TO = 3:91 posi (W31,W30)

To help determine what rear came in your car originally,we need some more info.Is your car an automatic,4-spd manual,or 3-spd manual? Does it have AC or non-AC?

 

Brian,

Did Canadian cars also get the O axle for '70? I know in 69 that 442's from Canada had a Chevy differential.

Brian

 

Thank you BOTH for your info; this is exactly what I was wanting to know.
The car came equipped with an automatic trans and A/C, if that helps with the ratio choices.
At one point this car war really 'duded up'. All the drive train had been sprayed 'Hurst Gold' (front springs, a-arms, sway bar to axle). But, it has a 10 bolt under it, it might even be a "Chevy" housing??
The front clip, motor/trans have been yanked long ago, has signs of "other brand" motor mounts being welded in place, etc. This girl has had a busy/hard life.
Pull up my user name, only have one other thread, gives some data on when we found it. She will be a beauty when done though!

 

Oldsmobile A body cars were built in Oshawa Ontario Canada from 1964-1967 using the BOP 8.2" 10 bolt & in 1968 & 1969 using the Chevy 12 bolt. Production of Oldsmobiles at the Oshawa assembly plant ended with the 1969 model year run. So there is no such thing as a Canadian built 1970 442.

Just an FYI 442s were only built in Oshawa for the 1968 & 1969 model years. No early 400 cid engines were ever assembled at the Oshawa plant or imported into Canada for installation at the plant & as a result no 1965-1967 442s could have been built in Canada. Only 330 powered & 6 cylinder powered cars were made there at that time. No 1964 442s were assembled @ Oshawa either.

There is a red 1965 442 in Texas that has been at a classic car dealership for a long time. Lovely car that the seller claims is Canadian built. It is a clone on a 330 powered Cutlass. The seller refuses to accept that the car is not a 442. Buyer beware it is not.

 

It would be pretty trick to find the build sheet associated with your 442, that would have the axle ratio printed on it right?

 

The RIGHT HALF ONLY was found on top of the gas tank; pinned down with masking tape, the other half was exposed to drainage/elements and is completely gone. I do not recall seeing the axle options printed on it.
Great thought though

 

Here is a link that helps ID the Olds axles


http://www.supercarsunlimited.com/in...id/diff_id.htm

 

If it was originally an automatic with AC,it would likely have come with a 3:08,or 3:23.It could have been ordered with the 3:42.
Where was your car built? If you found a sheet above the tank,I am going to guess Freemont,CA. It seems like a lot of the Freemont cars had the papers above the tank.
Regardless,the 10-bolt that is in the car now is not original or correct for a 70 442.

 

Absolutely correct, build sheet clearly says Freemont. Thanks for dumbing this all down; after all, I am a CHEVY guy! lol

 

I don't know where you are but I have an "O" type that reportedly came out of a 70 442 with 3.23 gears. It is not a posi. I am in the Dallas area. I am going to sell it. Shipping on these things is expensive.

 

Wichita KS, 5 hour trip; I will keep yours in mind. Thank you!

 

I have two SD-code 3:08 posi rears.I have a few SF-code 3:23 posi rears,but I think they are spoken for.I know there is an ABF dock near Witchita,as I have shipped there before,and will be shipping another one soon.I thin right now,it's about $200.00-$225.00 to ship there.

 

The 3:23 rears are about as street friendly as I would consider. Keep me posted if their availability changes.
Thank you Sir!