rr480

Can anyone tell me what ratio I might have

Charlie Jones

That is the part number and casting date ,
There will be a number stamped at about the 7 o clock position on the diff as you face the pinion , post that .

rocketraider

Default SF ratio was 3.42. Others were available.

Blownolds

This. It's a stamped number about 1/4" high, not a cast number. It's on a pad next to one of the bolts (right about 7 o'clock). It will be either a single digit, or it MIGHT also have a single number with a letter next to it (I seem to recall Olds as having used "L" for "locking". What is important is the single digit number. This is the code for the factory ratio (assuming it never got changed out by somebody, or the factory didn't stamp it wrong). You can find the code chart online.

monzaz

Here is a picture for reference...

59-59-59

That 8L = 3.42:1 anti-spin rear

monzaz

This is an example for the guy that needs to know where to find it. Jim

59-59-59

In that thing called a service manual

monzaz

What exactly are you talking about?

Your IDing pictures I put up for the guy that needs to know what he is looking for on his third member... at the 7 oclock position. So I posted the example pictures of the 8L 3.42 posi and the 9 3.23 open stampings in the casting....

We do not know what he has as he has not posted his picture or given the number that is on his third member.



Your helping the wrong guy. reread the post at the top.

Jim
JD

GEARMAN69

Not to be too obvious but besides codes, if he wants the ratio of a limited slip/locking diff just do the yoke turns to one wheel turn in neutral on jack stands. This method is totally accurate on a "Posi" aka "Anti-Spin" car.

Simple as a hair past 3 full yokes turns is 3.08 , 3-1/4 yokes turns to one wheel is 3.23 , 2.5 is 2.56 simple stuff. You never know if the chunk has been swapped from another year Olds or Pontiac on 59-64 9.3 31 spline stuff same as other styles.

rr480

Thanks for the information

Charlie Jones

8L = 3.42 posi

OLDSter Ralph

Thanks RR, Monzaz and Charlie.
I had the same question and the pics helped a lot. When you have old crusty things, knowing where to look and for what helps a lot. Its nice to have helpful information. I am trying to track down things on my '64 Starfire. I have figured out I have a real 1964 Olds Starfire from the VIN number and other helpful threads.
RALPH