Audio Systems: radio mutes, system measure, highway speed

Question
i have 98' sable and the radio mutes when i put the car into gear

Answer
I doubt the radio is saying mute, correct? It's probably shutting off, or loosing volume. Probably more related to the voltage of the charging system. Measure the car's voltage, idling in park, idling in gear, and at highway speed. They should all be very close to 13.8 VDC. If they are not, the alternator should be replaced. Another issue might be the remote volume control that some of the sable's came with. It could be broken, and suceptible to vibration and/or impacts. It can be unplugged completely with no ill effects.