A while back a noise developed from the rear, under 30mph a kind of train chugging sound eminates with wheel rotation. Slight vibration, enough to wiggle loose things but not noticable at speed. I attributed it to some tires I got off a car that had sat & had potentially had flat spots.

But, one of those blew out and the noise remained after the replacement. Doing brake pads today I measured .152mm of lateral play on the driver's side, between rotor and retained brake pad. The sound of it moving is pretty close to what I hear while driving.

So, what might be broken?

Checked the diff fluid, pretty clean & at proper level.

Thanks for any ideas.
-Sean
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1966 122s, 1970 142s, 1974 142e... Blue is beautiful