In most cases, the ½-ton Ford 4x4s and '80 and later 2x4 pickups came with the preferred 31-spline ... 9-inch build tips to help you make the swap on any 4x4. It still requires a few specialty ...

Currie Enterprises offers a selection of Ford 9-inch third members set up for 31-spline axles, which is what you want when you're making a lot of horsepower and torque. This includes a choice of ...

31-spline, PN M-4204-F31A, shown). Ford 9-inch rearends have a third "extra" pinion support bearing located at the rear of the drive pinion. Other rearends have only the traditional center two ...