Ground Force Drop Spindles Provide 2-2.5 inches of drop for today's hottest trucks and sport utilites. All Ground Force Spindles are constructed of ductile iron and reinfoced in high stress areas with heat-treated axel shafts. From the high-strenght alloy bearing surfaces to the built-in steering stops, each model is deigned for maximum wheel back spacing of 3.5 inches to fit a variety of wheels.