'65-'67 Olds rears

[WMACHINE]

Are your 4.11 4.10 gears original GM gears or aftermarket? You can look on the edge of the ring gear outer diameter it will have a GM part number and tooth count of the pinion and the ring gear and some letter suffix codes. Jim

Okay, I'm back. Opened up the rear on my May '67 built '67 442 with the P rear. Previously, when I spun the rear and counted, I came up with the 4.11. Well, bad math? Anyway, they are 3.90s and match the TH stamp on the tube.
But most interestingly, it has the same 4 pinion carrier as the aforementioned '67 W-30 rear of similar vintage.
I'm reasonably sure the 3.90 rear is original.
So it makes me wonder how extensive the the 4-pinions carriers were for Olds. Obviously they ended with the '67 models. But how early were they used?

[monzaz]

OK, BUT those gears are 1970 gears...My guess is that the guts are from a 1970 gto. Jim

39 10 is the ratio 3.90 then GM (obvious trade mark) then you have 2 6 70 month feb or june (2 or 6) then year 19(70) then O A code for part maybe??

What bolt size are the ring gear bolt heads. 11/16 or 3/4 socket head needed to fit the ring gear bolt head. Let me know. Jim

67 should have 3/8" bolt which will have the 11/16" bolt head
68 is the cross over year and can be both.
69-72 will most likely have the 3/4" bolt head

[WMACHINE]

It is buttoned back up so I can't measure. Does this pic tell you?

Are you sure about the date? Can't be like 2 (Feb) 67 (1967) 0 (shift or ?)

[monzaz]

definitely could be... That is a 6 before the 7 yes or maybe G? Hard to see from the picture....I dd call it 6 and yes it certainly could be 67. What was the ring gear bolt head size once more? On this 67 ? 11/16" or 3/4 " socket? Jim

[WMACHINE]

That definitely reads GM 2 670 OA
Right before the 6 is a vertical mark, but it really doesn't look like a stamp. If it is, it is a "1".
The ring in the '67 W30 rear (which was originally 4.33 and replaced at some time with 3.55s) reads:
39 11 GM 9 6710
I don't know how they are supposed to read except for the ratio!

Re the ring gear bolt head size, I didn't think to check it before I buttoned it back up. Can you tell anything by the pic on my previous post?

[monzaz]

could be either or? If it was 7/16 bolt heads it is 1970 1971 1972 for sure.

If the bolt heads are 11/16 socket then it is 1968 1967 1966 1965 1964 etc. Jim

[WMACHINE]

Okay. Does the later '70 '71 '72 7/16" bolt carrier fit the earlier ('67 in this instance) P housings? In other words, are the carriers interchangeable?

[monzaz]

Yes they can fit the old housing and vise versa....BUT you must use the 7/16 and or 3/8 ring gear with the correct posi unit with the same drill ring gear flange holes. SO the gears and the unit have to stay as one package deal. Ok? Jim

[WMACHINE]

Axles interchange?

[monzaz]

Not if the 67 is a sealed bearing... Which I am sure it is. 1964-1972 all have the same spline 28 and 60 degree spline angle...BUT in late 1968 they used a NON SEALED bearing with the seal pressed onto the axle shaft between the bearing and the retaining plate. The early 1964 -1968 early have sealed bearing with seal pressed into the axle tube housing.

Jim

[WMACHINE]

Yes, sealed bearings they are.
Thanks, Jim. I guess that completes our '66-'67 Olds 10-bolt primer for now.
I'm still trying to find out how extensive the use was of the 4-pinion carriers in these P rears with Oldmobile, but that's just leaves a very small part of the puzzle.

[monzaz]

I would say a very small amount were 4 pinion posi unit in 67 as the 12 bolt olds rear was introduced in that year in the USA cars for the w-30 etc. so I would say only the first half of the year and MAYBE canadian cars got them. Jim (That is a guess-ti-mation)

I am assembling a T# 67 68 rear right now with the 31 spline axles and 3.91 gears 672 posi unit 12 bolt olds. FINALLY found the housing for these posi and gears I have...The axles came with the housing and that was a BIG find. Jim