Lug pattern for after market rims

Okay, how do i tell what kind of truclients I have? Listed above is the truck I have, it is an extended cab 4x4. I am trying to buy some after market rims and do not know the exact lug pattern, it is six lug. How do i measure the rest and buy the rims? they have a few options like DXL extended cab 3.4l v6 and SR5 extended cab 3.4l v6 and a base extended cab 3.4l v6 and a regular extended cab 3.4l v6. it does not give a 4x4 option. so how do i tell which one I have? please help and how do i measure my lug pattern? Thank you.