in my research, there was tale that a lot of the valve covers were the same and they only changed what the name was when cast.
while i can't verify the veracity of that, and i wasn't around then (obviously), i take that with a big grain of salt to think that weiand or MT or [insert any number of other name brand] covers would be cast together with pro/stock. the low line chain store stuff just swapping out? yeah i'd buy that.