arodenhiser

Prepping to replace my diff oil and I finally cleaned enough sludge/dirt/undercoating to find some numbers stamped on the front of the passenger side rear end tube. Can anyone out there ID what I should have by these numbers.

RA 0627K

As I understand it, a Canadian built Cutlass would have come with a Chevy rear. It is a posi but what is inside I do not know yet. One time while on the hoist I guestimated the ratio as a 4.10. I don't have I high top speed, but getting there is fun.








I will show some pics when it's apart too.


Thanks in advance!

allyolds68

I think you weren't turning both wheels (or holding one, I can never remember until I do it myself)

I'm pretty sure it's a 2.73

GAOldsman

The only thing I could locate is a peg leg 3.07:1 truck rearend from a '68 chebby

GAOldsman

http://www.gmcpauls.com/67-72_chevy.htm

allyolds68

I got the 2.73 out of the 68 assembly manual, page 4-109 which is the axle usage chart for GM of Canada. As long as that axle is original to the car it's probably right.

If it's a Cutlass or C/S with a 2 speed tranny with a 350 2 or 4 bbl I'd say it's definitely right. The standard tranny for the US for that tranny was a 2.78

The axle usage table is on page 4-106 for GM of Canada

GAOldsman

Yep I see that now it is an open "C- axle" w/2.73 gears and 41-15 teeth on gears

arodenhiser

Thanks everyone for your quick responses. I think that someone has opened it up and did some swapping. I can leave 20 ft of two lines if I want too. I am sure it is a posi. The previous owner used to drag the car in an amateur class of "run what you brung" racing. My Cutlass seems to be quite a franken-cutlass. Body is colour A, left door colour B and trunk colour C.

Factory it was a 2 bbl 350 , 2 speed. Now it is a 4 bbl 350 @~9.5:1CR, with a 350th 3speed. When on the hoist we spun the wheels, both moving the same direction and are "locked" together. We counted 10 turns on the tire to ~41 turns of the driveshaft.

I will take a picture of the internals when I pull the cover off.

arodenhiser

Here's what i found inside.....



The larger driven gear has 41 teeth. The smaller drive gear (the one far back inside ) has 10. My simple math says 4.10 gears there. Not original. Not a surprise either.



Here is the stamping on the driven gear

1 GM 3862526 10 41 4 69

If I were to write this on a spec sheet what should I call it?

Chevy 4.10 Posi trac?

Is any other description more correct?

One last question. Should I use a paper or rubber or RVT/silicone to seal it up with when I reinstall?

Thanks again.