I need to change all of mine but I'm not sure how many I need. I'm gonna do front and back on my 98 4x4. So if someone could tell me how many I have and maybe a good place to get them from it would be much appreciated! thanks

 

One for where the front driveshaft meets the diff.
Two for the rear: one where it meets the transfer case, one where it meets the diff.

If you like people, NAPA has really good greasable ones. If you like the interent, you can't go wrong with www.rockauto.com.