here are some numbers i found on the ten bolt i removed from my 69 gm65,3894859nf,2345,67890 thanks Greg

Just foundry casting numbers, won't tell you exactly what the ratio is or what car it was designed for.

You need to find the stamped codes on the front side of the axle tube inboard of the carrier.


Casting numbers are raised and were done at the foundry.

Stamped numbers are recessed and were hand stamped in a "gang fixture" (all at once) by the final axle assembly plant.

Front side of passenger axle tube. It will start with 2 letters.

Mark