Eaton Posi assembly date

[bcmiller]

All Eaton 12 bolt posi carriers received a stamped assembly date code. The code was in the format of letter / number / letter. It seems be be fairly well known that J was used for 1969. Do we know the letters used for 1965, 1966, 1967 and 1968?

Thanks in advance.

[Lee Stewart]

https://i.postimg.cc/Kjk7yrnH/screenshot-7623.png (https://postimages.org/)

https://www.onedirt.com/tech/drivetrain/12-bolt-rearend-guide/

This help?

[big gear head]

He is asking about the letters stamped on the outer edge of the ring gear flange on the Eaton Posi case. I've got cases that are stamped F, G, H and J. I think everyone knows that J is '69, but what are the others? The 12 bolt was produced from '65 to '72. Did these codes continue the same on the Eaton Posi case to '72?

[m22mike]

All Eaton 12 bolt posi carriers received a stamped assembly date code. The code was in the format of letter / number / letter. It seems be be fairly well known that J was used for 1969. Do we know the letters used for 1965, 1966, 1967 and 1968?

Thanks in advance.

I think they used letter A to k. For the year (did not use I ) J being 1969 you should be able to count back from there.

[BCreekDave]

So you could have a JJ (October 1969)? By the chart letters are for months up to 1971

[bcmiller]

It would make sense that they didn’t use the letter I for year - but I swear I had one a few years ago with the year letter stamp being I. I could be wrong or suppose it could be later. Although they stopped being used in production in 1972, they were made much later.

Here is a later one. Year code JC - maybe 1993?

[bcmiller]

So you could have a JJ (October 1969)? By the chart letters are for months up to 1971

The format is letter number letter. Here is one stamped C 22 H from a 10 bolt 3 series posi.

[big gear head]

So assuming that the E would be for the first year of production in '65, then F would be '66, G would be '67, H would be '68, J would be '69, K would be '70, L would be '71 and M would be '72? Can anyone verify this with something from '70 to '72?

[MarcDant]

Here is jan. 22 assembled rear gear.

[bcmiller]

Thanks for posting that. The posi assembly date stamp is late 69, fits fine for a Jan 1970 axle assembly.

Would anyone have data from other years they would want to post from original axles?

[bcmiller]

Nobody?

[MarcDant]

This unit is from Nov. 11 1968 assembled rear .

[bcmiller]

Thanks! That confirms I was used for the year.

I bought a May of 67 complete original rear end yesterday and it had H for the year.

So it looks like H for 67, I for 68, J for 69. Thanks everybody!

[big gear head]

There is the I. So I was used. So F wold be '65, G '66, H '67, I '68 and J '69. I wonder if K, L and M were '70, '71 and '72?

[bcmiller]

I wonder too. Hopefully we can get more data points.

[luv2sixty9]

So what is D 3 A?.....April 3, 1973
I have one with this stamp.

However, it has a casted date on the side of "40" (February 9) and I thought that was the only date.

[luv2sixty9]

I have another one with this stamp. B 1 G " Feb 1, 1966?

It has a casted date on the side of "24" (January 24)

[bcmiller]

So what is D 3 A?.....April 3, 1973
I have one with this stamp.

However, it has a casted date on the side of "40" (February 9) and I thought that was the only date.

Thanks for posting. Is it in an original rear end?

The only way to really verify dates is if it would be a complete original assembly.

[big gear head]

If it's a 12 bolt Eaton with a '73 date then it would not be an assembly line unit because the 12 bolt was not used after '72.

[luv2sixty9]

The two that I have listed are loose units that I have lying around, so I don't know what they are out of or the actual date.

I was requesting assistance with the stamped date for the cast dates I know how to read.

[luv2sixty9]

If it's a 12 bolt Eaton with a '73 date then it would not be an assembly line unit because the 12 bolt was not used after '72.

IDK, it's an original #140 Easton Posi

[bcmiller]

The two that I have listed are loose units that I have lying around, so I don't know what they are out of or the actual date.

I was requesting assistance with the stamped date for the cast dates I know how to read.


Ok - I think you decoded the B 1 G correctly. Not sure on the other.

[bcmiller]

Verified G is for 1966 from an original 67 Z28.

[HuggerSS]

Do we know wether “H” or “I” was used for 1968? Mike mentioned that he was not sure if “I” was skipped it the alphabet. Thank you in advance for any clarification!

[m22mike]

Based on post #12 and the photo there of a 1968 unit it looks like ... I....was used. Often times with dates and castings it is not, that is why I said I was not sure.

Mike

[big gear head]

I'm going to bring this up again. I've got a 12 bolt 2 series Eaton Posi with a code that looks like A 6 70, but could be A 6 7C. Did they change from a letter code to a number code for the year in '70?

[ssl78]

I have a 11D of 68 car this is the original posi unit

[ssl78]

rear end date

[bcmiller]

Thank you SSL78.

That shows I was used for both the month and year.

[GotGrunt]

I’m bringing this thread back to the top because I need help with a date stamp. It looks to be D 3 D, which would be April 3, but I’m not able to figure out the year.

[big gear head]

What is stamped on the edge of the ring gear flange?

[GotGrunt]

What is stamped on the edge of the ring gear flange?

There’s nothing stamped there. From what I understand, they were either stamped where mine is or down by the ring gear flange, but not both.