I was using 4wd last night and when I put it back in 2 I heard a knocking noise from the front end so I put it back in 4 till I got home. When I got home I crawled underneath and saw no exterior damage to the tranSfer case or the front diff or driveshaft. The driveshaft does have about a half inch of play to either side though which leads me to believe u-joint. I this correct? I also don't think my 4wd is working either

 

yeah, you probably need to replace the front u joint

 

Ran to autozone today. Picked up a new u joint and then crawled under when I got home. Put the trick in 2wd and checked to see how much play I had. It spun all the around and I looked and my passenger side cv was spinning as well. So it's not the ujoint. Of course. I just replaced the drivers side about 2 weeks ago. Are these common parts to go on these trucks? I'm just gonna save for a solid axle at this point

 

Not really a weak point, the truck is just getting older.