1969/1970 12 bolt rear service replacement part? 3969341NF

[Badshifter]

I was just given a 12 bolt pulled from an ex race car and want to see if I've decoded the numbers correctly. It's just the housing, no gears, axle or diff.
Casting Number 3969341NF - late 69 early 70?
Casting Date C190 - March 19th 1970?
Axle Tube stamp C OS (or) C QS 0421G2 - OS (QS) 2:56 4WD (4 wheel disc?) April 21st Detroit Gear 2nd shift?

Is the 4WD indicative of a Service Replacement Part?

Thank you for any help.

[KurtS]

1970 3.07 axle.

[Badshifter]

Thank you Kurt.

[Rossterman]

Correct for a 70 SS camaro

[ko-lek-tor]

Most likely Nova. Measure length. Here is a chart:

[bertfam]

Most likely Nova.

COS is a 1970 3.07 Camaro axle.

Ed

[rare396bronze]

You beat me to it Ed. There is no CQS listed in Chevrolet by the numbers. But COS is listed as Camaro 3.07. Nice find. 70 12 bollts are hard to find since they did away with the 12 bolts on Camaro after 1970.