Gears & Axles - Weird noise, I think its U joints but assure me

So for the past 4 days I went on a little vacation about 4-5 hours away and did alot of driving to say the least. Well my car never made this noise I'm hearing until I got back home last nite. Not even joking it never made this noise until I got home and sat down for a little bit before I took my girlfriend home.

Well we get in my car and leave to take her home and thats when I hear this weird whining noise while coasting in gear. Reminds me of really loud road noise like a truck with big mud tires or something. Only happens while coasting not when I am giving it gas. Also when I put in in neutral and coast the sound goes almost quiet but it is still there. So I get under today to check and put it on jackstands and have my bro drive so I can listen. Good news is it is NOT coming from the pumpkin, sounds more like from the driveshaft. The driveshaft has a little play in it both up and down and it spins a little before the wheels have any movement. I just don't know what kind of allowances it has. The shaft also had some light scratches on it where it is hitting on something while it spins so it is moving. For sure though the sound sounds like it's coming from there and not the pumpkin. Also made a little clunk noise under the car in the shifter area when putting it into gear sometimes, don;t know if that is my poly mount or not though because I have had that on forever.

bump cuz im going through the same exact problem

Sounds like gears too me, but if you are sure its not coming from there then go ahead and replace your u-joints, its pretty cheap and easy.

its gears. u-joints are just spinning all the time. they dont care if you are accelerating/coasting/decelerating.

when my 12-bolt on my Hawk started doing that, i was afraid it was coming from the trans or something. really just a matter of the fact that the rear/DS/trans are all connected... and there is a hole in the floorboard right under your hand, so the sound can sound like its real close to you.

as you stated, the sound changes based on how much throttle you are giving it. mine did the exact same thing... you could find a sweet spot where it would be quiet. sound got worse with every trip to the track, and only went away when i replaced the gears (totally unrelated to the noise issue). and i'm sure my new gears will start doing it again once i start going back to the track.

if the car see's a lot of drag time, its probably permanent. if its pretty much a street car, i'd try changing the fluid and see if it shuts it up. if you car is a 94, i assume you have a clutch-type differential, so make sure you put in the LSD additive.

The drive shaft should have no play up or down or back and forth. It should also have no play when turning it as that would indicate backlash. From my novice and I do mean novice knowledge, play up and down in the driveshaft indicates a bearing problem. Prolly needs new bearings or the gears need to be set again. You would know if the gears were broken too, so its prolly not catastrophic.

The reason I don't think it is the rear is because even with the car in the air and someone driving with me under it, I could not hear anything coming from the pumpkin. The sound was definitely coming from up by the driveshaft somewhere. I did burnouts and a few launches and drove through curvy roads and I could not get it to clunk at all. All I can get is the humming noise while coasting in gear. Anyway tomorrow I am replacing the U-joints and will post up they fix it.