I don't know driveshafts well enough to judge how much slop is too much, and I don't see a spec in the manual (though it does spec total runout at 0.6mm). The only truly bad one I've seen was in our '63 Scout, and that thing was so whupped it was sagging in the middle. I wouldn't expect an IFS truck to put enough stress on the slip joint to wear it out. If you can't make it go clunk wiggling it by hand, I would call it good enough--but, again, I'm not a driveshaft guy.
I have heard of driveshaft weights coming off, though not on one of these that I can remember. I would expect to see an obvious bare spot and busted welds where the weight used to be if this had happened.
The diff bushing symptoms don't match yours from what I remember. Just something to check while you're in the neighborhood.