Acceleration "SQUEEK"

[LS 1st Gen]

So along with a "clunk" while decelerating, I'm now getting a squeek from the rear end area while accelerating from a coasting roll.

 

Basically if I am coasting along while during normal driving above and give the truck some gas, there is a slight delay(normal I assume), and then a loud quick "Squeek!" as soon as the acceleration begins. Is this maybe a Ujoint or slip yolk problem? I've also read about the exhaust flapper valve causing a squeek. I'm starting to get nervous about this rear end...

 

(5.3 4x4 Crew, standard bed)

[fondupot]

Its probably the flapper. clamp it open and see if the squeak goes away.

[20L8TSierra24]

Its probably the flapper. clamp it open and see if the squeak goes away.

I can guarantee its the adaptive valve. Clamp it and your problem is solved. I did it on a rental suburban because it annoyed me too much and I didn't want to hear it for a week.