I have a 2000 2wd 2500 automatic with what sounds like 2 different roaring noises. The first one is the front tires as they are starting to cup....But I can't find out the cause of the cupping and the noise is worse turning left. The second noise almost has a metallic sound to it but I can't tell for sure. I thought about wheel hub bearing but I can't find any play in them and the only other thing I can think of is u-joint but that doesn't make much sense to be a little louder turning left and it is louder going uphill. Any ideas?

 

Cupping is the result of Alignment, balance, or poor tire design. I can't see which is your issue from here.
On the second metallic sound. Does it also have a odor to it. That would help identify.

 

Thanks for the reply. I have not noticed an odor to the seemingly second noise. I took the driveshaft out tonight and am going to go ahead and replace the u joints. They have been in for at least 100k so it's time anyway. They are rusty and a bit tight so it might be part of the issue. An interesting note on the u joints is they say spicer on them but I can't seem to find a part number for replacement. The driveshaft is steel and one piece.

On the tires....there is a low spot on every other tread (in the same line) at the back of the tread. Then the next tread is back to regular height and then goes downhill to a low spot. I checked the tow in and it is pretty much exactly square.

 

Plenty brands of joints avbaliable, NAPA probablly has Spicer and others Also. Staly away from offshore pieces. Good job on figuring joints probable noise. Rough and rusty will do it every time.