I agree with Austin on this one; it's ludicrous to even think that some quantity of 69 Camaro owners even knew what their rear end code was before the last few years (the fellas on CRG are the *extreme*, not the norm for Camaro owners!), and even more extreme to believe that a bunch of Camaro owners crawled under their car and 'peened' on that 'unrelated' C out in front of the axle code. I've been a car nut for over 50 yrs, a Camaro fan since they were introduced, past owner of '68 and 70 Z28s, and an owner of my '69 Z28 for 40 yrs, and until a couple of years ago, I had NEVER even thought of crawling under and checking the rear end code on any of those cars (I knew they were original to my cars by other factors, and didn't even know there was a code on them until getting involved with CRG).
Anyway, I think the idea proposed by Bryon that 'camaro owners over the years' had peened off the 'C'... (I'm still laughing at the idea).. is pretty ludicrous.
IMO, there are only two possibilities for the rears where we 'see', or imagine we see, a damaged 'C' out in front of the axle code:
1) roadway objects, rocks, etc, happened to hit that area...?
2) OR.. there was some confusion in the axle plant, given the changing of the axle code schema for the 70 model year cars, combined with the extended production of the '69 Camaro into the 70 model year.
Note: Corvettes were also extended production... Was there a corresponding change in Corvette axle codes? ( I have an original '69 Corvette I've owned since 1988 or so which I've never checked a rear end code either...)