Factory chrome covers are the same metal stampings as stock painted covers for the same year, the combinations of welded on looms can be different. They have baffles welded inside, they have the notches for the gaskets to mount to. Some have plug wire looms and wire harness looms welded on like a painted cover. 67 GTX has the welded on bracket for the heater hoses. The oil breather cap is a push on style on the standpipe made into the valve cover. The breathers and pcv valve and hardware are just the same as painted covers for the same year car. See the trends, they are just like the painted covers in so many ways.

The covers on the green car above are not factory, they are Direct Connection. They are a chrome plated version of mid 70's stock BB covers. The easy wat to tell is the raised center, 1/4 turn oil fill cap, and the breather goes into a rubber grommet.