Revolution Gear and Axle, Replacement series, Rear axle shaft for Ford 9 Inch 76-77 Bronco w/11X2.25 Brakes, Left Hand, 27.19 Inch 31 Spline Upgrade. Revolution replacement series axles are made from 1541H Steel and utilize a state of the art computer controlled heat treated process. The use of better material and better heat treating process gives our replacement axles a 10 Percent increase over the OEM axles.