Lycoming Aircraft Engine Cylinder Head & Barrel Assembly featuring factory casting number LW-12433. Designed for wide cylinder flange (WCF) engine architectures, this heavy-duty assembly is a baseline component across popular Lycoming 4-cylinder and 6-cylinder powerplants, including the O-360, IO-360, O-540, and IO-540 series. To the best of my knowledge, this is what they are. Working condition is unverified, and these are being sold strictly as-is / untested engine cores for overhaul or parts.