Take a look here:http://www.camaros.org/forum/index.php?topic=1726.0;all
Part of this thread talks about the 69 baffles. It also says they are hard to find...
Jonesey is right. The baffles help the car run cooler when you are "stressing" the cooling system and motor by running the AC on a hot day.
Ed posted the 68 AIM page on this. I see no reason why you can't install them after the other work is done, but the smart thing to do would be to check your 69 AIM.
There are many more seals, etc. involved. Does your car have those?