Revolution Gear and Axle, Replacement series, Rear axle shaft for GM 8.2 and 8.5 Inch 73-77 Chevelle and El Camino, fits both Left and Right side, 30.5 Inch 28 Spline (OE# 1255801 / Hollander# 447-1067). 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.