I know the servo unit was a very consistent part through the late 70s, but is the best way to determine the proper date of part to see if would be appropriate for my 69 Charger?

Thanks,
Joe

The 1968-1969 servo is different than the 1970+ servo. The system that shut the speed control off when the brakes are applied were vacuum powered in 1968-1969 and in 1970 that was changed to an electric shut off system. That meant differences in the servo. The later electric shut off was much simpler and can be adapted to the 1969 and earlier cars. Here's a pic of an NOS servo with a 1969 date code.

servo comparison pic

Thanks for the detailed response. It was exactly what I needed.

Joe

Thanks for bringing this topic up.

Are there and dates or part numbers stamped into the parts?
Or were they just ink stamps?

My experience is that there were many more servos without any date code than with.