Originally Posted by aztrailerguy
I own a 2003 Ford 250 V10 6.8l 4x4 super cab. I always tow in Drive with over drive off. Should I be driving in 2nd Gear instead going up hills? My TT gross tow weight 8800lb.
Always put the tranny in "D" and let the computer decide which is the correct gear. That computer is a lot smarter than I am. And it's probably a lot smarter than you are.
But there is one exception. In hill country where you are going up and down and down and up, causing the tranny to frequently shift out of and back into overdrive, then kill the overdrive with the button on the gearshift lever until you get out of the hill country.
Some folks say to not allow the truck to "hunt" through the gears. But your tranny is programmed to not allow hunting. If you tranny is often changing gears, it's because the terrain is going up and down, not because of "hunting".
Another exception I personally used on my F-250 when towing heavy was to manually kill the OD before
the computer forced the downshift to climb a grade. I could downshift out of OD smoother than the computer did it.
lock out overdrive if you are not in the ups and downs hill country. Your MPG will take a big hit when OD is locked out. And never downshift to 2nd gear if you value MPG. If you are overloaded and towing with OD locked out, the computer is smart enough to know when a downshift to 2nd is required to climb a grade.
Second Part Question. How do I know if I have a 3.73 or a 4.30 Rear Axle Ratio.
Look on the on the Federal Certification Label on the driver's door frame- the sticker that includes VIN, month/year of assembly, tire size and PSI, paint codes, and several other codes. The code under AXL or AXLE will be your axle code.
The 2003 F-250 3.73 and 4.30 axle codes are:
• 31 = 3.73 non-limited slip, F-250/Excursion
• C1 = 3.73 limited slip, F-250/Excursion
• C3 = 4.30 limited slip, F-250/Excursion
Another "shade tree" method is to jack uprear of the pickup, put the tranny in neutral, and mark the driveshaft. Turn one rear tire one full revolution while watching the mark on the driveshaft. If the driveshaft turns less than 4 full revs for one tire rev, then you have 3.73 ratio. If the driveshaft turns more than 4 full revs for one tire rev, then you have 4.30 ratio.