Linkert M25 1940 HARLEY E, EL - 1941 F, FL

The M25 if installed in 1940 would have a cast iron manifold and if in 1941 it would have a brass manifold, (The brass one's weight would be approximately 3 oz heavier than the cast iron - 13oz vs 16oz I believe.) 

See 1941 BRASS INTAKE MANIFOLD INFORMATION