A-R50356-AI Insert, Exhaust Valve (Std)One New Aftermarket Replacement Exhaust Valve Seat Insert (Standard) Fits John Deere Tractors This exhaust valve seat insert is pressed into the cylinder head to provide a hardened, heat resistant seating surface for the exhaust valve. It is designed for the Fits John Deere 6 404 Turbo Diesel engine and must withstand the high temperatures and pressures of exhaust gases to ensure an airtight seal and optimal engine performance. Sold individually; a