Seriously considering 2010 SD V10 3500 DRW Crew Cab pickup. Problem is I want it with 4:30 gears for towing, yet $;30's are only available in Chassis Cab not pickup. Why??? and can it be special ordered with the 4:30's somehow?? The F350 Pickup only lists 4:10 as optional yet the F350 chassis cab is available with the V10 and 4:30 ratio. HELP Please with this question.