Decoding / Identify valve covers... Motion?

[rbernat]

i believe if there ever was a standard for valve covers it had to be late 69.i have seen many styles on phase three and non phase three cars.like copo i have yet to see the polished finned valve covers on a pre70 car.my phase three 69 nova came with m/t valve covers and the biscayne with the standard chrome units.i have seen the ad showing the chrome units with ss-427 script.i believe that was for promotion only.
rich