Unexplained noise coming from rear axle area

[RichieDart]

I have '72 Scamp and 73' Valiant 4 dr. Both are slant six 7.25 rear AT cars.. Both cars make a "whooshing" noise when I drive them. Noise is identical in both cars. Noise gets louder as speed increases. I notice a slight drag and reduction of speed when I am coasting. My friend told me it was spider gears in differential making this noise. I had them changed in Scamp but noise and drag continued. I just bought the '73 Valiant last month so I haven't really had time to investigate it. I pulled drums off Scamp and every thing was proper back there. Could it be something dumb like backing plate rubbing or possibly axle bearings? Scamp has 80k on it the Valiant has less than 30K. Has anybody experienced same? Any suggestions would be helpful. I've had a few Darts with same setup but never experienced this situation with them. Could be a Plymouth thing? Thanks

 

[motorpirate]

video with sound might help?

 

[Darter6]

Re-check the backing plates where the shoes ride. Check for deep wear groves.It sounds like a problem we had on a 68 Dart.Pulled the shoes,cleaned and welded the groves up and sand flat.Noise gone. Just a maybe.

 

[mycuda]

Does noise weaken when you hit brakes at all? Without hearing, guessing axle bearing play causing some sort of drum drag.