forum.jdrace.com

]Hello Mr. Jim.
I have a Oldmobile 12 bolt Type O posi rear end with TO stamped on the back passenger axle tube. I took off the cover and found 588 on the posi,which I take it to be 28 spline.
The gear ratio is 3.91 from what I found on the ring gear,11A43. The housing has 402227 with CFD 4 cast next to it,which I believe is a 1970 rear end. My question is where is the casting date of the housing located. I found a stamp # of 344 close to the filler plug and was hoping you can shed some light on what it means.
Thank you for any help you can give me.

From what we know there is not year on this casting 1970 was one year casting so really no need for one the 344 is the Julian date so it stands for the 344th day of that 1970 year. Pretty sure it was December 10th of 1970.
1970 will have a OILED axle bearing system and was the only year for this in the 12 bolt olds rear.