If these are the old Airtronics (I think that is the Sanwa type) with the ribbed and rather thick shell as compared to modern connectors, you should not plug them in as the servos will be reverse biased and will burn out in seconds. If the red lead is not in the center of the plug, do not use them. However, you can rewire the connector so that they can be used by interchanging the two power leads, usually the red and the black leads. Some of these old servos had two black leads so you have to find which one is the signal lead and which is the ground or negative lead then reverse the red and the negative wires in the connector to use them with a modern receiver.