A-body splash shields the same?

I've got the OEM metal splash shields from my 67 vert and a set of plastic shields from some later model A-body. I've placed them side by side and on top one another for comparison. Pics in a older thread here somewhere. Yet to find a difference. The rubber flap added to the metal ones does add a small bit of width. That area is incorporated into the plastic ones. Maybe they wont rest quite as tight to the fender. Maybe I'll need to add a rubber flap to the plastic ones. Wish I could state what car these plastic ones came from. Anyway... I will use the plastics if possible.