What is the ford f150 h9 axle code?

The Ford F-150 axle code H9 indicates that the truck has a limited slip differential wit a 3.55 gear ratio. A limited slip differential has the ability to shift the amount of power to one tire or the other depending on the amount of traction and slippage that is occurring. If one tire is slipping the differential will provide more torque to the tire with more traction and decreasing it to the one that is slipping. This is good in wet conditions or in the winter during snowy weather driving. The gear ratio lets You know how many times the drive shaft has to rotate for the tires to make one complete rotation.