Hi Mike
This is just a result of my design theme for the car. So, personal preference
The black front bumper is intentional, as I wanted a blacked out front end, so my bumper, billet grill, and all of the headlight and hood trim is satin black powdercoat.
I also did not want any chrome or brightwork below the window line. So you see my mirrors, door handles and lock cylinders are also black.
But, I did not want a black rear bumper, so did that body color.
Your observation on the rear quarters is interesting. Great question. I don’t see many ‘69 or ‘70 coupes/convertibles at car shows, so will need to do some research on that.
My sheet metal is original, except for the hood and trunk lid. My car was built in November of 1969 at the Dearborn plant. So, maybe it does have left over ‘69 rear quarter panels. I also removed the front and rear side marker lights, so it does look much different than stock. And, no emblems, letters, or rocker panel trim on the car.
Vic