I recently saw an original owner '66 Dearborn with an estimated build date of March 11. I met the owner who works at a nearby Auto Zone and after talking to him for a bit invited me to see his car. His father bought it and had been passed down to him, claiming that it spent little time outside since the late '70's. The car is totally original, tires and all, except for the battery.
Anyway, I spent a lot of time looking at it and while helping him trying to free up the motor, I noticed that the Balancer was the same color as the engine; faded and a little greasy but definitely blue.
Mind you, this was just one car. Does it apply in general? I don't know but there is at least one that is blue.
Ray