I could use some help too. I know my diff. is a Positraction but not sure what ratio. It was double stamped at factory. Codes are: QJ 0516G1 and QC 1101C. Casting date is H246. What do I have? This is the original rear. I haven't had the cover off to check number of teeth. I have checked number of turns of driveshaft to 1 turn of wheel and it just a tad over 3. Drives like it's geared pretty high with the 4 speed. Thanks

The QJ is a 3.07 posi 12 bolt. Not sure why the double stamp. The QC would be a 4.88 posi 12 bolt. Wonder what one you have?

Thanks Daniel. It's strange why it would have the double stamp. Ratio has to be 3.07 making the QJ code correct.

I don't recall seeing a double stamp on an axle before, seen it before on a trans. Must have had problems with it and it got sent back to Detroit Gear for repair.
Looks like the QJ date matches your car.

I have seen a '67 12 bolt with a double stamp once before. One stamp was 307 posi, the other was 456 posi. The original gears were gone and it had 410 gears in it.