I guess you would disconnect the d-shaft from the diff first, and then move the ujoint around. It should be totally smooth, and there should be zero play. Then you could do the same to check the other 2 if necessary.

I read that you aren't supposed to re-use the 4 driveshaft bolts. I think you can get them fairly cheap.

I don't think greasing the ujoints really helps. If you need bearings, you need bearings, no way around it. They don't have grease fittings, do they?

Greg