I have a 05 trailblazer LT 4x4 with the I6 none extended body. i just replaced the fount and rear u joint. the reason for doing was when shifting from reverse to drive i would hear a large banging noise. so i though it was u joints. well yes the u joints were bad but the noise is still there. not sure were or what it is. but unfortunately it sounds like it is coming from the back of the Transfer case. anyone know what it might be. it is mainly heard when your foot is on the break and you slowly shift from reverse to drive.