What does 2007 Ford E-250 axle code 22 mean?

The axle code "22" on a 2007 Ford E-250 refers to a rear axle with a 3.73 ratio. This means that for every 3.73 revolutions of the driveshaft, the rear axle turns once. A higher number (like 3.73) indicates a lower gear ratio, providing more torque for heavier loads or towing, but lower top speed and fuel economy compared to a lower number (e.g. 3.55 or even lower).