Just at a glance at this post, I might have missed it said already, but the rear antenna location on the 70 T/A's were on purpose, a lesson learned on the 69 1/2 road runners & Bees with fiberglass hoods which encountered a lot of radio signal interference that would normally be shielded from the steel hood.

I have a pic of an original location of antenna on a 69 1/2 RR but I'm apparently too stupid to figure out how to make the pic small enough to go this site...

Anyone needs the pic just drop me a line and i'll email it to you.

As to your original question Why is there a hole in the drivers side? Well, it was, after all , the 70's - maybe the previous owner added it to hang the all too common for the time Racoon Tail so he could look in the rear view mirror and watch it a flappin in the wind. Not helpful? sorry.