Here are some instructions as to what you will need to do.
If you have a dial indicator, it will be the best way to measure ball joint play. But, there are things you can do to check it without one and, if they are really bad, you won't need one.
Here what you do:
1. From the axle, use a good floor jack to lift one of your tire off the ground. If you don't have a good floor jack, set your axle on a jack stand to hold it up securely in place.
2. From the side, place a long pry bar under the tire and have someone lift it up and down while you watch the lower ball joint for axial (up and down) movement. Any movement more than 0.050" is too much and would indicate that your ball joint is bad. Of course, if you can see this movement with your eyes, it's definitely bad.
3. Next, grab the tire at the 12 and 6 o'clock position and try to rock it back and forth while you have someone watch the upper joint for any movement. Any radial (side-to-side) movement more than 0.060" is too much. Again, if you can see the movement with your eyes and without any dial indicator, it's probably bad as well.