The kidney grill on an E9 or an E3 can be easily dinged or dented and it can be changed or swapped out so this easily leads me to believe very few of these grills on present day coupes are original. This is hard to believe now, but at one time, our treasured coupes were daily drivers, so it not hard to imagine that many original owners probably went through a few replacement grills.
During the first 6 years of ownership of my first CS in the late 80s and early 90's, I bought at least 3 new all aluminum grills due to how frequently they were dinged up. So in essence, these grills were consumable items back in the day. Present retail price for a new all aluminum 5 bar grill from BMW is about $400, but back in the early 1990's, they were selling for about $70 and probably quite a lot cheaper back in the 1970's.
Count me in as a fan of the black 5 bar grills as I've never really like the bulkier looking 4 bar units. Have never like the cheesy looking all aluminum 5 bar grill either, with all the chrome on the coupe, BMW should have had the grill made of a heavier chromed alloy.
My first CS came with a fully chromed grill and gave the coupe a regal appearance similar to vintage MB all chromed front ends. Unfortunately, the chrome started flaking off after about a year due to the fact that aluminum is so hard to properly chromed well. All the replacement anodized grills never really measured up.
My present coupe has the later black 4 bar unit, but I'm hoping to replace it with a nice black 5 bar grill.
According to the original orange parts book, the black 5 bar grills, part #: 51 13 1 826 809 were fitted to CSLs only. But back in the day, these NLA grills can be bought and swapped in place of the original or possibly ordered when the car was purchased new.