There's on the way out is all. Shouldn't fall out from under your truck or anything unless they've been like that for a long time.

One thing to note is that all U-joints have a certain amount of "slop" in them but you just may not feel it. Every time you "gun" the engine when you're at a dead stop, the sudden turning of the drive shaft will wear the u-joints more severely than if you started more gently.

Not saying you do that, intentionally or what, but the fact is, from my experience, this is what wears the U Joints quickly.

Another thing that kills them is not coming to a complete stop when changing gears from Reverse to Drive and vice versa.

HTH,

Ray