Not sure about 68's but on 69's, headlight washers and extra solenoid on the wiper motor with hoses that go to the headlight washers that are installed above the headlights.
Chrome trim around the roof and door edges and around wheel openings. There is a huge list in several of the books available, showing all the extras that come with it. Good luck, I know the owners of 68's and the guys from Camaros.org will give you all the definate clues here shortly.
69RS 350/255 LM1,TH350,Dover White,Blue Vinyl top
F&R spoilers,pdb,ps,am/fm,4.10 Posi.,A/C,
fold down rear seat.
My RS www.brainerd.net/~knudsen/69RS
I don't know if this holds any water but look at the vacuum hose check valve. My 68 6 cyl had the original one and its a one-in and one-out fitting. I could not find a replacement for that type anywhere. All the repos I found were like the kind on a 69 which are one-in and two-out.
Of course the vavle could have been replaced at some time on an original RS.