I locate squeeks simply by dribbling or spraying water on the belts.
Some belts like to stick to the pulleys, and that for sure makes them squeek. My solution is to deglaze the drive edges.
I had one of those in 1976, with a 340 in it. I sure miss it. After a few years I gave it to my younger brother when he got old enough to drive. I sometimes wonder what ever happened to it.
