Revolution Gear and Axle, Replacement series, Rear axle shaft for Ford 8.8 Inch 87-96 F150 and Bronco, Left Hand, 33.18 Inch 31 Spline (OE# E7TZ4234B / Hollander# 447-1574L). 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.