When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Trying to find the factory stamp on the rear diff that will identify date and ratio on a 69. I understand it is on the right side. Hoping to find an HT Mark. Can anyone point me in the right direction, or do any forum members have an example to show the location? Thanks.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
Originally Posted by Gold Dragon
Trying to find the factory stamp on the rear diff that will identify date and ratio on a 69. I understand it is on the right side. Hoping to find an HT Mark. Can anyone point me in the right direction, or do any forum members have an example to show the location? Thanks.
On our '78 the diff was stamped underneath. It's actually not visible on a '78 without removing the small heat shield. Here's a photo of what it looks like. It is on a "pad" on the case, adjacent to the join with the cover. You can just see the spring mounting plate in the top of the photo. The Tie Rod mount is at the bottom of the photo. The numbers are pretty haphazard and it took a while to identify the date, ratio etc!
Last edited by Stephen Irons; Jan 16, 2017 at 04:07 AM.
Same on the 69', except there is no shield. It is on the bottom of the diff case right next to the plate securing the leaf spring. Usually full of oil and grease, may need to clean it good to read it.
Joe
Hi GD,
The stamped information on the carrier case flange typically consists of and indicates:
a digit…..shift the differential was assembled
2 68) or 3 (69) letters….. ratio code
digits….date the differential was assembled (month/day/year)
a letter…. plant at which the differential assembled (D…Dana, E…Eaton, etc.)
In addition, there is a date cast into the side of the carrier case and another cast into the rear cover.
Regards,
Alan
Here is a picture of the bottom of the differential case from a 69 where you will find the stamped information giving the ratio code and date of assembly. Cast dates of the pieces are located on the drivers side for the main case and the back cover cast date is on the passenger side as Alan has shown pictures of.
Going right to left:
The first digit is the shift number, in this case a #2.
The next digits are FA which stands for 370 ratio Heavy Duty
The next set of numbers are the date of assembly 1-14-69 (Jan 14, 1969)
The last digit is the plant, W, (Warren)
Last edited by ed427vette; Jan 16, 2017 at 10:40 AM.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
Originally Posted by ed427vette
Here is a picture of the bottom of the differential case from a 69 where you will find the stamped information giving the ratio code and date of assembly. Cast dates of the pieces are located on the drivers side for the main case and the back cover cast date is on the passenger side as Alan has shown pictures of.
Going right to left:
The first digit is the shift number, in this case a #2.
The next digits are FA which stands for 370 ratio Heavy Duty
The next set of numbers are the date of assembly 1-14-69 (Jan 14, 1969)
The last digit is the plant, W, (Warren)
Don't want to hijack the OP's thread, but it's interesting how much easier the '69 numbers are to interpret than the '78. I still have one character that is really only guesswork!
Last edited by Stephen Irons; Jan 16, 2017 at 12:08 PM.
Hi Karol. If I understand correctly it means High torque.
No such mark or reference for any 69 rear ends that I'm aware of. I could be wrong but never heard of it. What you may be confusing it with and hoping to find is an HD rear end. This would be determined by the two letters stamped after the shift number. In the example I showed, the letters were FA which would be a 370 posi rear, (HD) Heavy Duty, made for the 427. Sometimes the HD rear could be found on the 350hp small block but I am not sure if they did it on purpose or just to move the assembly line along. I don't know enough about the assembly in that area to give accurate information only to say there are original 350hp cars out there with heavy duty rears that seem to be original to the car.
Last edited by ed427vette; Jan 16, 2017 at 05:30 PM.
Differential stamping
