Thank you for all your responses, however this noise occurs in park (as oldsinner noted) and as a function of engine RPMs rather than the speed of the vehicle--or rotation of driveshaft/rear wheels. Checking it out in a few minutes, hopefully beating the thunderstorms...

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth