Axle ratio
How many times the driveshaft turns for each turn of the wheels.
A numerically higher axle ratio, such as 3.73 instead of 3.31, multiplies torque to the tires and is often required for the top tow cell. It can cost fuel economy and is not available on every cab. The 2026 F-250's 22,000-pound conventional cell is a 3.31 axle with the high-capacity package, not 'any diesel'.