Yes there are the obvious ones that feel very flimsy to the touch. I was hoping someone would chime in giving me a really great shortcut of sorts.
Its the hard to access, or time consuming joints that I was hoping to find a solution for. The big suckers holding on our trailing arms, etc. The ones that aren't easy to put a load on and feel while you're solo in the garage at 10:30 at night.
I guess you're better off putting a mileage on them and swapping with regularity for reliabilities sake.
When I first built my T100 I had 7/8" or 1" on the upper links of the 4-link and when they wore out I could grab the bed and push it side to side and feel the play in them. Later when we put the bigger rear end in it I upgraded to 1-1/4" (same thats on the lower links) and they rarely wear out. But I also don't drive it enough...
The official way to test is measuring the torque it takes to rotate the ball. An easy way is to check for side play using a lever, checking it on both sides when installed since the arms are usually pressing hard on one side or the other which can hide the play. Side play is easier to check than end play, but they both reveal the same thing.