A-146163BH-AI Seal (204017)One New Aftermarket Replacement Oil Seal for Bush Hog and Agricultural Equipment This aftermarket replacement oil seal (type HM18) is a shaft seal used in Bush Hog and other agricultural equipment to retain grease and prevent contamination from entering bearing assemblies. The seal installs on a 1. 625 inch shaft and fits a 2. 332 inch bore, keeping drivetrain and implement components running cleanly and reliably in demanding field conditions.