I came across a pair of corvette valve covers from what i can gather are from 1959-to 1966 or 67ish, they are aluminum and have corvette in cursive on them. They are no different them most except these valve covers have top mount oil breathers on them. I have looked at various models and none that i have seen have these top mount oil breathers? can anyone help

Clint

 

perhaps someone just drilled a hole in them and bought breathers and o rings?