Late 69 Differential Code Stampings

[Lawrence M.]

Re: Late 69 Differential Code Stampings

Jamie, I found the rest of the info I had from my Q15 built 1969. The Diff cast date was I 19 9 the ring gear (3.55) was dated 9 69. The engine was the L46 small block.
Larry

[Jamie F.]

Re: Late 69 Differential Code Stampings

Tom, very close to Gary's dates. Thanks!
I love this stuff!

[Tom M.]

Re: Late 69 Differential Code Stampings

Tom,
Do you know the casting date of your diff case?

vin # 36083
# on my M22, P9R10C = OCT 10th 69
# on rear axle,FA91869W2, = SEPT, 18TH 69 , 3:70 HD Posi

hope this helps , Tom

[Jamie F.]

Re: Late 69 Differential Code Stampings

Tom, Great stuff!
My car is just 85 after yours. Where your Diff was assembled a month before mine. Yours is a 3:70, and mine is a 3:55, so maybe they had more of one ratio then the other? Or used less of one ratio???
Does anyone know if there is a breakout of what rear ratios where sold on '69? How many 3:55's, how many 3:70's etc?
I guess I will take another look for that W or C.
Thanks for the pics and info!

[Tom M.]

Re: Late 69 Differential Code Stampings

Tom, Great stuff!
My car is just 85 after yours. Where your Diff was assembled a month before mine. Yours is a 3:70, and mine is a 3:55, so maybe they had more of one ratio then the other? Or used less of one ratio???
Does anyone know if there is a breakout of what rear ratios where sold on '69? How many 3:55's, how many 3:70's etc?
I guess I will take another look for that W or C.
Thanks for the pics and info!

Just glad i can help

[Steven H.]

Re: Late 69 Differential Code Stampings

Jamie

Mine is a P23 VIN 194379S736819 car and I strongly believe this to be the original rear; I hope this helps.

1CAO11 24 69

[Jamie F.]

Re: Late 69 Differential Code Stampings

Thanks Steven. Interesting that your date code is one day After the body start date. Would be worth going back to look at what day of the week your car was started. Maybe a Thursday and the rearend was built on Friday, shipped and then installed in the car on Tuesday??? Don't know. But I've never seen one that close datewise. Nice picture too.

[Steven H.]

Re: Late 69 Differential Code Stampings

Jamie

From what I have studied; the P23 on the trim tag was the start point of the build and the car was usually finished a couple of days later, does that sound right to you?

[Terry M.]

Re: Late 69 Differential Code Stampings

Jamie

From what I have studied; the P23 on the trim tag was the start point of the build and the car was usually finished a couple of days later, does that sound right to you?

P23 was the date when the trim tag was applied. In the case of early C3s, the trim tag was applied after paint, but before trim. Your couple day estimate to "off the end of the line" is probably accurate -- allowing for weekends and holidays.

I think one would have to define "start point" more accurately to take care of this end of things, but that is not germane to this discussion.

[Steven H.]

Re: Late 69 Differential Code Stampings

Terry

Please come over to my thread where your opinion and facts would not only be germane; but appreciated as well.

Steve

https://www.forums.ncrs.org/showthread.php?t=70805

[Jamie F.]

Re: Late 69 Differential Code Stampings

Steven,
It's not impossible, but I would normally doubt that a rear end made in Warren MI on Nov. 24th, would end up on a car that's trim tag date is Nov. 23rd, but it could have happened.
If your car took longer than normal to finish the rear end could of shown up and been used, especially if they were out of that ratio.
A 3:70 ratio was not a the highest volume unit and if specified it could have been an early version of JIT!
Someone else may want to chime in and give their opinion.

[Steven H.]

Re: Late 69 Differential Code Stampings

Jamie

I was going on the assumption the date was stamped at point of install much like the VIN's on the block; why I assumed that I'm not sure.



If the dates were stamped on the rear at assembly of the rear and assembled in MI; then you are correct, there is no way this is the original rear.

Do you know for fact the dates are stamped on the rear at assembly of the rear?

I will re clean and double check all my numbers tonight.

I am here at NCRS for an education; these are exactly the type of things I need to learn.

Steve

[John H.]

Re: Late 69 Differential Code Stampings

In '69, with the trim tag applied at the beginning of the Hard Trim Line (vs. later C3's in the Paint Shop), the differential was being assembled in the basement rear suspension subassembly station about 30 minutes after the trim tag was installed on the car.

[Steven H.]

Re: Late 69 Differential Code Stampings

John

Now that is some interesting information.

[Jamie F.]

Re: Late 69 Differential Code Stampings

The Diff. carrier itself was not assembled at St. Louis, but at the plant stamped on the housing, W is Warren. What John is refering to is the sub assembles being put together in the basement.
So that date is when the 3:70 gears were installed and at what plant.