Are my hubs the problem???

[gjkap]

I have an 04' xterra that I bought new that has recently been making a heavy metallic clicking noise in the front end in 2wd(most audibly with the windows open and driving 5-25mph on uneven pavement/old brick streets and going straight ahead). I don't need to be turning the steering wheel to hear the sounds and I don't feel it telegraphing in the steering either. I got under the vehicle to check for loose parts/unusual wear and found the the front drive shafts (?) (not sure if that's what they're called) have some side to side play which when pushed/pulled in the direction of their respective hubs closely mimics the sound I hear when driving. The cv boots which these shafts go through are intact and without damage. Also, the other day I decided to take it into 4wd-LO (it still makes the sound in 4wd) and it was a mother trying to get it back into 2wd. I really had to push hard on the lever. I'm not sure what the deal is seeing that I'm not that savvy when it comes to cars but I'm figuring it might be that my auto hubs are worn. Anyone got any ideas on this? I'd hate to get it fixed without knowing what I'm talking about. My X has got about 87,000 miles on it too. Thanks.