The one that I found when I googled it and that I tightened was one of the bolts that holds the caliper to the whole hub assembly. It takes an 18mm socket or wrench. You don't even have to pull the wheel. Just turn it so you can access the back side, locate the caliper and look on the assembly just in front of the caliper. They are between the caliper and the cv joint, and there is an upper one and a lower one. The way I found it really easily was to grab the caliper and shake it.

 

oh ok I am 2wd so I dont think I have these bolts...I was trying to figure it out but that makes sense...thanks for your response!