Exhaust Valve Fits John Deere Gas B 50 TractorOne New Aftermarket Replacement Exhaust Valve Fits John Deere Two Cylinder Letter Series Tractors This aftermarket exhaust valve is a direct replacement for the Fits John Deere Model B and 50 two cylinder gasoline engines. The exhaust valve seats in the cylinder head and controls the release of combustion gases from each cylinder. Two exhaust valves are used per tractor and this part is sold individually. Fitment is restricted to Fits John Deere Model