Different antenna mounting on A-bodies

I was cleaning my laptop and found some pics I took when I was over at Redscampis house a while ago. We noticed that the antenna mounting areas were different on my 73 dart and both his 72 scamps.

Here is my 100% bone stock original 73 dart custom.



Here is the 72 Scamp that I traded to him for the 48. I'm 99.9% sure that this is the original fender for this car.




Here is his other 72 Scamp that may have had the fender replaced at one time. See the weird indent? My 73 Scamp didn't have that on it's original fender. Anyone else have this weird indent, what cars did it come on?




Here is a just because pic.