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U Joint or what?

B2200 mazda: I’ve recently got a screechy noise only when in gear but gas pedal NOT depressed. Could this be an indication of a bad U joint noise? Or? The noise seems to be coming from the rear chassis of car. Noise seems worse if going in reverse. Possibly coincidentally I started noticing the noise after a shock absorber worked its way loose, causing lots of racket. (The mechanic who’d installed it has since tightened it.) Would all that rumbling from the loose shock have caused something to break or work loose? Or is it just age of vehicle (22 yrs) By the way, the noise is very similar to a wire scratching metal. I also have had the classic thunk noise of a u joint, for a longer period of time-- never looked into though.

So, why are you writing this instead of looking at the u-joints? I agree, sounds like a possible u-joint problem. On a truck like this, it is really easy to check. Get under the truck and roll the driveshaft back and forth with your hand. If the joints click or you see gap in movement from one side of the joints to the other, you have your answer. Is this truck a one-piece shaft, or does it have a carrier bearing? Carrier bearings can also wear out around this age.