Oh i didn't realize you had a bed light, that changes things. the basic setup for a bed light equipped truck should be very similar to a dome light only truck with the extra wire being positive for the bed light coming from the dome light and the other two for switched ground and constant positive. the bulb in the cab light is tied to the dome light so they both come on at the same time as each other. if you don't care about the functionality of the bed light you can simply leave the wire for it disconnected and use power and switched ground to the doors for it to work. if you use a wood spacer you will need to ground the base of the new light to metal for the manual on position to work otherwise you will only have light from the door open position on the light and one of the doors open.