This coupling assembly connects the cutterbar drive to the gearbox output on the header of a grain harvester. It transmits rotary motion from the drive shaft to the knife-drive mechanism, converting rotation into the reciprocating motion that moves the sickle sections. The set includes two bearing shells, two grease nipples, and the complete bolt kit required for installation. A worn coupling produces excessive backlash in the knife drive, leading to uneven cutting and increased vibration at the cutterbar. The original components match the factory geometry of the bearing saddles and bolt pattern, so no shimming or re-drilling is needed during replacement. On reinstall, torque the bearing-shell bolts to specification and apply grease through the nipples before operation.