how do i change the u joints in my 2004 ls?

you need a u joint press. autozone loans them out or you can buy one from harbor freight if there is one near you. You have to mark the drive shaft at the pinion (where it bolts to at the rear axle) scribe a line across both metal plates before unbolting it so you know its orientation, they are balanced and failure to do this can create vibrations and wear. after you unbolt the 4 bolts pull the drive shaft out of the transmission (have rags on ground as a small amount of transmission fluid could spill) remove the "c" clips on each u joint end with needle nose pliers, press the joints out, press new ones in, make sure each new c clip is in place and re attach the drive shaft aligning the marks you made earlier. The whole process will take a newbie 1-1.5 hours but probably save you well over $120 by not having to take it to a shop. Tools needed: u joint press, socket set, needle nose pliers, mallet. (you can use the mallet and a socket bit to tap the u joints in to get them started..possibly seat them all the way without the press)