97 Yukon noise

Hi Everyone! I have a 97 Yukon and it just recently stated to make this loud and annoying sound when I drive about 30 - 40 mph. I pulled over immediately and checked underneath the Yukon to see if anything was stuck..nothing. I turned on the ENGINE and pressed on the accelerator WHILE I was in (P)ark just to check if the sound comes back and it didn't. I only hear the sound when I am driving. ONLY when I am driving I hear the sound and feel a little Vibration coming from underneath the YUKON. Other than that it runs smoothly before the 30-40 mph. Steering feels fine. ANY SUGGESTIONS?


...........I just went out side to take a look under the YUKON after THE RAIN. I just started to look around to see if anything was loose, missing, or broke. I took a couple of photos of this part that I turned with my hand and I heard the sound that I hear when I am driving, JUST not as LOUD! Any Suggestions?

http://img162.imagevenue.com/loc1116/th_83088_DSCF4953_122_1116lo.JPG (http://img162.imagevenue.com/img.php?loc=loc1116&image=83088_DSCF4953_122_1116lo.JPG)http://img161.imagevenue.com/loc1107/th_83096_DSCF4954_122_1107lo.JPG (http://img161.imagevenue.com/img.php?loc=loc1107&image=83096_DSCF4954_122_1107lo.JPG)http://img101.imagevenue.com/loc794/th_83109_DSCF4955_122_794lo.JPG (http://img101.imagevenue.com/img.php?loc=loc794&image=83109_DSCF4955_122_794lo.JPG)http://img21.imagevenue.com/loc1143/th_83111_DSCF4956_122_1143lo.JPG (http://img21.imagevenue.com/img.php?loc=loc1143&image=83111_DSCF4956_122_1143lo.JPG)

Yes, pull the drive shaft and have the u joints checked, keeping in mind we cannot hear this noise. but you should see if there is any internal movement of the u joints in the shaft while still in the truck.

Is the U joint that big copper color part? Is this a job that I can do? If yes, any link to instructions. TY

Due respect here, but by asking that question it tells me you should have this done/checked by a pro.