Front driveshaft- Inside the cardin joint between the two u-joints is a centering ball with needle bearings it went on mine and it made aweful noises took forever to figure it out.

 

I had a driveshaft made for the Silverado I had before my (bless her) JEEP. Agreed, it was a great investment, and a cheap one too. The driveshaft purchased from a store would've cost over 100. I bought the origional driveshaft and two new yolks to a machine shop after calling around. (Calling around before you go is mandatory!) Make sure the shop is a little hungry for work and they'll hook you up. The shaft they made for me was an overbuilt monster that all my friends envied... for 40 bucks! The shop even told me that if it wasn't right, to just bring it back and they'd fix it. It was a great deal.

 

Also... when all else fails, change the bearings... cheap and easy, never hurts.