Was cleaning up a set of 1970 442 rear bell brake drums and noticed some markings, etc and thought I'd post some pics/thoughts.
You can see some of the original green paint on the rims, the manufacturers name: Centrifuse, 35454 which I am guessing is a part number and an A with a 0 under it. I'll guess that translates to A=January 0=1970 which fits with a February 23, 1970 build date.

Any thoughts on if my "A0" translation is correct?

 

Centrifuse refers to a spun cast process that marries the cast shoe lining to the steel bell.
The circle MW = Motor Wheel co.
The 35454 = part number for std 9 1/2 x 2" bell drum and is/should be the original drum for your car.

Availability started the same time the O rear end became available, 1967 through 70... Cutlass/442, except wagons.
The Oshawa cars with the Chevy rears did not get the bells.

I've heard a couple of meanings for the Ao:
Assembly outboard (drum) which makes little sense, to me.
Assembly Oldsmobile, plausible as the bells were exclusive to Olds.
An OEM quality stamp, plausible.

I researched this YEARS ago as my 68 has these drums and the car is painfully original.

 

Perhaps A.O. Smith Company made the core. They made frames and brake drums. "A O" could be the logo used at the time.

 

Hi,
did you happen to weigh, or know the weight of these drums compared to the finned drums?
Or even a rough idea from anyone?
Thanks in advance
cheers
Update for Answers I think are correct.
Regular Finned Drum 16.5 lbs
Bell Type Drum 12.5 lbs