Take a little tippity tip from me once you find the mirror bolt holes in the reinforcement bracket inside the cab.
Take an automatic center punch (the kind that fires the punch when you push on the plastic handle) and place it in the center of the hole on the inside of the cab and push it enough times to make a dimple on the outside of the cab so you can drill it from the outside.
Start with a small drill bit to make sure that you hit the center with the punch.
