Looking up from in front of driver's tire, remove these two 13mm/1/2" nuts with a deep socket. They are locknuts to keep from coming loose and the studs have been out in the weather getting road grime thrown on them. So man up. Bonus points if you crawled under there, wiped them off and squirted penetrating oil on them as the very first step. Wear your Safety glasses! Don't come out from under that truck crying like a little girl with something in your eyes.