This PTO o-ring seals the connection between the tractor output shaft and the implement driveline. It sits in the groove at the PTO shaft housing, preventing lubricant leakage and keeping contaminants out of the coupling. A worn or hardened o-ring allows oil to weep from the housing, which can lead to bearing damage if the lubricant level drops. This original AGCO part is molded to the same cross-section and durometer as the original seal, so it seats fully in the groove without requiring additional sealant. On installation, ensure the groove is clean and dry before pressing the o-ring into place.