Howl from the rear end

[Phil_F_NM]

My '78 300D developed a howl one day on a drive from Jersey City to Philadelphia. It worried me to no end and I stopped three times on that first drive down to Philly to check things.

The sound doesn't happen until the car has had a few ten good miles or so of 35mph+ driving. The noise is a single tone, never going up or down in pitch, it just gets louder sometimes. It will vary volume with the articulation of the rear end and I'm sure it is coming from the driver's side wheel.

There is no play in the wheel when I try to rock it side to side to check for a bad bearing (though I admit that is not an accurate test.) When off the ground, the wheel doesn't grind at all.

My theory is that one of the parking brake shoes is becoming a little more "sticky" after friction warms it up and then it starts to vibrate the brake surface like a violin bow on a string.

Could this also be a bad CV? Both CV axles feel tight when I try to move them forward and back as well as up and down. The side to side play is there as is expected.

As I'm in Jersey City, it's illegal to work on my car in the street and I don't have a garage. I also don't have money for the repair if an indy mechanic were to do it but I definitely can't afford to be without the car.

Any thoughts on the noise? Any thoughts from north Jersey or NYC area members on where I could do the work myself?

Thanks all!
Phil Forrest