Need help diagnosing weird sound from rear end

[AubAlum0509]

My friend has a club car DS, pretty sure it is a 98 or 96 model. It is emitting a strange noise from the rear end. At first I thought it was a fender getting caught in the tire, but after removing seat and taking it for a spin, we realized it wasn't from the fenders. We are not sure exactly where it is coming from, but we are thinking either the rear axle or the motor.

https://www.youtube.com/watch?v=chiGh1jGw1s

The sound really starts at 0:06-0:09 seconds, then goes in and out, seemed to do it more when going faster. Around the 25-29 second mark, it gets the loudest.

Anybody have a clue what this is? sorry the video and audio isn't the greatest, apparently I had phone where it could detect the wind blowing.

thanks in advance for the assistance. It is greatly appreciated.