That valve cover was used on my '50 COE and probably on all the advance design COEs. The valve cover lies just beneath the "doghouse" so the only quick access to add oil is with the breather tube with cap. In fact my truck had a later 235 and the original cover was fitted to the engine for the very same reason.
Kent

1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix