Ahh ha! A solid solution to another Firebird mystery. Anyone know how many Palladium Silver '69 Firebirds? And...what, if any, serial numbers are on the '69 fenders. I found these: 5A 1M(left fender) and 5B 23(right fender).
It's been a while since I looked but I'm pretty sure they are date codes so you can see if they match with the rest of your car/body. as far as uniformity with Chevy and Pont. I'm pretty sure GM kept date codes the same. When I checked my car the brake booster master cyl. and steering box had all the same numbers/letters (except part numbers) as Chebby.
I guess I remembered wrong on the fenders then but I know the master booster and steering box were the same. There is a lot of detailed info on that site if you sift through there is a lot of crossover stuff. some of the things I remember were about the astro ventilation insignia on some of the early 68s just like our '' bird glass". and pictures of the minor differences in lower control arms for the 7,8 and 9s. Interesting stuff when your trying to sleuth together what parts have been replaced through the years on our cars.