Revolution Gear & Axle, replacement series, rear axle shaft for Chrysler/ Dodge 9.25" 4/3/84-93, 1/2 Ton 4WD, fits both left and right side, 31.62" 31 Spline (OE 4137429/ Hollander 447-1398). 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% increase over the OEM Axles.