Here are a couple pics. There are 9 small bolts that hold the plastic trim to the valance. They have captive washers on them and say SEM on the heads.
EDIT........................
I just re-read your post and I think your talking about the gray rubber filler pieces between the body and the bumper. There are three pieces on the front of the car. The center piece screws to the grill. The outer pieces screw to the header panel and clip into the front fenders. They are NOT repopped. A lot of guys take them off and push the bumpers in like the 72's. I've seen NOS ones listed at Tony's Parts and at Arizona Parts.
Here is a pic of the drivers side end piece.
I don't really have a good picture of the center piece. You can just barely see part of it in this pic.