I have a 04 sierra z71 4x4. when ever i decelorate down to around 20 or so then hit the gas i hear a single Clank it sounds like coming from under carriage not the engine. could this be my u-joints or what could it be?
It could very well be a U-joint. Park on a level surface, set parking brake, block a wheel so it won't roll, and jack and block vehicle up unless you can fit under it without raising it. Climb underneath and rotate drive shaft back and forth while looking at each u-joint.
