If I stand alongside the rear wheel and I push my '97 F150 sideways back and forth there is a banging noise coming from the REAR. This happens if I push from either the driver side or the passenger side. Can anyone tell me what the problem is. Thank you.

 

Axle shafts in the rear axle are held in with c-clips and a pin and there is a certain abount of play in those and that is what you are hearing, if they break then you wil see your axle shaft and tire come out from the axle tube and role down the road I do not think you will be able to break it under normal driving.