Although the 1972 models still allowed special order RPOs, this vehicle would normally come from the factory with a 3:.31 open end 12 bolt rear diff and TH 400 trans. (the posi and 4 speed would have been special order) The 10 bolt and TH350 more than likely came out of another vehicle.I recently looked at a 1972 El Camino 454SS for sale. It had the "W" code in the VIN, but to my surprise the car had a 10 bolt rearend and TH350 trans. Did a W car ever come with this drivetrain?
BTW, I passed on the car. Thanks