Love my wife's new ride, but one minor thing it has a light clunk on downshifting. U-joint or tranny going out? Either way, price was right, I don't mind putting some money into it.

 

Could be slack in the diff too. Just a thought

 

Is this the suburban? There's a TSB in reference to a drivetrain clunk that outlines replacing the slip yoke for a nickel plated one. I replaced my u-joints and slip yoke when I installed my trans in May and so far my clunk is gone. A quick fix (or diagnostic aid) would be to remove the driveshaft, and coat the splines of the slip yoke in some good quality grease, such as marine grade, that will not break down easily. If the noise goes away after greasing, you've diagnosed the slip yoke as the culprit, and can either replace it with the nickel one or just grease it periodically as the noise returns.

Other possibilities include excessive play in the transfer case, rear differential, or u-joints

 

Yeah the suburban. Which what a comfortable vehicle that is. Man I like it alot. Did a road trip in it today with the wife on some errands. Very nice comfortable seats and all in there. I want another one for myself, but I commute pretty far so gas is more of an issue for me.

Today I don't think it really clunked at all. So I'll keep the nickel plated yoke in mind if it gets bad. That's the kind of answer I was hoping for though.