Wheelbase is based on the cab and bed configuration. If he has either a CrewCab 5.5ft Bed, Extended Cab/SuperCab with a 6.5ft bed, or Regular Cab/Standard Cab with an 8ft bed he has a 145" wheelbase. If he has a CrewCab with a 6.5ft bed, he has a 157" wheelbase. If he has an Extended Cab/SuperCab with an 8ft bed, then he has the fairly rare 163" wheelbase.