Side valve replacement left side engine case features a blank number boss. This case has the same oil passage for the outside sprocket shaft bearing as the original case. NOTE: Left side case must be fitted to existing OE right side case. Cylinder base surfaces and motor mount surfaces must be milled to match before assembly. *NOTE: Requires hole to be drilled in the left case. Cast in the bushing after the case race has been pressed in. Install the race and then drill the hole. *NOTE: Left side cases accept standard case race. FITS 1937-1948 UL OEM 24536-37 410-37 406-37 ACCESSORIES 8126-34 - Cadmium Motor Case Bolt Kit Stock 40-9968 - Side Valve Primary Chain Oiler Tube TECHNICAL SPECIFICATIONS Suggested to use with #10-0208 Sprocket Left Side Case Race Standard.