One Aftermarket Replacement Gearbox Compatible/Replacement for IM402, IM502 High Speed 1:1.93 Ratio. 40hp rated, 1-3/8"-6 spline input shaft, 1.57" X 12 tapered spline output shaft and 1:1.93 speed up ratio. These gearboxes can have a square housing configuration and are identical in mounting to the OEM gearboxes. These have been used as OEM gearboxes on the World Agritech Corp / International Machinery IM402 and IM502 series rotary cutters which featured slip clutch PTO shafts. ***NOTE: This gearbox will not fit the IM400, IM500 and IM600 models as they have a smooth input shaft*** Works On gearbox with a 12-spline output shaft and a 1-3/8" - 6 spline input shaft this gearbox will work. Bolt pattern is 4-3/4" on center hole to hole and 6-3/4" center to center of bolt hole on diagonal. . The mounting holes form a square bolt pattern. *****Please note this gearbox is shipped dry and will require 16 ounces of 80 weight gear oil or heavier! ***** One Aftermarket Replacement Rotary Cutter gearbox, 40hp rated, 1-3/8"-6 spline input shaft, 1.57" X 12 tapered spline output shaft and 1:1.93 speed up ratio. These gearboxes can have a square housing configuration and are identical in mounting to the OEM gearboxes. These have been used as OEM gearboxes on the World Agritech Corp / International Machinery IM402 and IM502 series rotary cutters which featured slip clutch PTO shafts. This gearbox will not fit the IM400, IM500 and IM600 models as they have a smooth input shaft! If your gearbox has a 12-spline output shaft and a 1-3/8" - 6 spline input shaft this gearbox will work. Bolt pattern is 4-3/4" on center hole to hole and 6-3/4" center to center of bolt hole on diagonal. The mounting holes form a square bolt pattern. This is the high-speed version which will provide greater blade tip speed and provide a cleaner cut when mowing pasture ground. *****Please note this gearbox is shipped dry and will require 16 ounces of 80 weight gear oil or heavier. *****