Strange noises coming from rear-end

[Codypaul]

now all joking aside i hear strange noises while driving my '70 gmc. First noise is when i get on it or off the throttle. it clunks. now im pretty sure its the u joints and im not all to worried about it.

the second noise is more of a chatter. almost like a hollow pipe slapping against something. i only get this noise when down shifting or coasting down a hill.

My dad is a tech and owns his own shop. Rather than asking him i wanna figure it out my self Gotta make him proud.


any help would be great thanks!