On the way to the cottage an intermittent screeching sound seem to come from the radio speakers. My first thought was the radio had brought it or some unknown security system had fired off. I knew such a system was not factory on 1984 300ds so I turned the radio off.

Screeching was still present on an intermittent basis. So as I drove along wondering what the hell was generating the high pitched screech in the audible spectrum. I noticed the cruise was starting to act up a very slight amount. That made me think the amplifier was probably voltage sensitive. Plus I had installed new belts reciently.

On arrival at the cottage sure enough the alternator belt had stretched causing intermittent alternator output. The no charge light on the dash did not illuminate at all as far as I could tell. Nor just glow dull. I couild have of course missed it as it was a bright sunny day.

So as the output voltage changed so did the cruise control vary a little in concert. Now how the high pitched ocillations were generated is an unknown. No doubt as the voltage dropped a little something was breaking into oscillation. I am not going to try to find it by the way. I just mentioned this for people to think about .Especially if any complaints of a high pitched squeels source are ever asked. Easier to restore the voltage on those cars rather than source the culprit I imagine.

Also could be one in a million type of thing. Although I thought maybe I remember someone asked before about a screeching sound that was not a belt or bearing.