How can you tell if the U-joint in a 2004 Chevy Silverado 4x4 HD is going bad?

[Gus72]

Everytime I stop I hear a sqeaking noise in the back of the truck,when I take off again it stops.Don't know if it's a U joint,one of the brakes sticking,the rear diff.,etc.Whatever it is,it's making me crazy because of the squaking!Thank You