Antenna question part 2

So, after Indy Dart sent me pics of his Chargers antenna fender hole (thank you) in response to my previous picture request I realized the hole on my fender was noticeably smaller. I dug my old antenna out and it is certainly a smaller diameter and slightly different in design than the factory style replacement I have. I'll post some pics as soon as I can shrink the ones I have down to a postable size. I'm guessing this isn't some oddball factory option, at least it doesn't quite match any mopar style antenna I can find. That said, I can't for the life of me figure out why someone back in the 70s-early 80s would have gone through the trouble to do the sheetmetal and paint work to shrink the hole down to fit what appears to be essentially a factory type antenna. I just thought I would run it by the board for a sanity check before I break out the die grinder to open it back up to the right size. Thoughts?

After typing this up it occurs to me there's another option, I never found a broadcast sheet for my car, perhaps it was a radio delete car originally? The original dash bezel was butchered for regular am/fm stereo.

Pics added

What year is the car & is a radio coded on your fender tag?

Do you have a fender tag? Does it have a "R" code?

It does have the fender tags, been years since I looked at the decode i have of them, but for some reason I was thinking radio options weren't on the tag. I'll have to dig that out of my files.

***edit***
And just to avoid going down a rabbit hole unnecessarily, I'm not concerned with whether or not the car should be radio delete, I want a radio and its too far along to turn back if I was that concerned with it. I just want to make sure I don't hog out the hole if there's a legitimate factory antenna other than the commonly available one to put in there. Oh, and it's a 71 to those asking

In the 50's and 60's I worked for a Chrysler dealer, lots of the new cars came with out an antenna so we drilled holes to match the antenna the parts dept supplied us with, sometimes the new antenna was in the trunk of the car

Update: Nothing on my fender tag mentions anything about radio options

Lynch Road car?

Yes, Lynch Rd

Almost looks like a early GM antenna.