Ima' 9 man myself, and have never had much interest in--other than appreciating all old iron--the 7's and 8's. So I cannot say what is and what isn't on the 7's or 8's.
One thing I can help clear up is that parking lamps, and marker lamps are 2 different things: Parking/directional lamps are on the front--the ones with amber lenses. Marker lamps are on the side and have red lenses. I don't know if things have changed, but back then it was federal law that parking/directional lamps were amber in the front and all rear lights, excluding back-up, were red.
The problem I see is that a diagram won't solve anything because if they were an option, the diagram will show it. The thing is that the diagram will not tell you whether or not your car has marker lamps.
(My Pontiac factory Service manual has a wireing digram, but it only covers 69's. By the way, you can go to the libary and find the diagram, and a good reference libarain can find it for you. Clean your nails, turn on your charm, and she'll do all the work.)
Remember, parking lamps are not marker lamps, so that should help solve some confusion. I think that the 7's and 8's have the same fenders, but the fender extensions are different, and my best guess is that the maker lamp--if it has one--would be in the extension.
Seriously, you ought to be able to look at it and tell whether or not it has red marker lamps on the side of the fender or its extension. The diagram will show you the colors, but it won't tell you if the car has marker lamps. I'm sure that your observant enough to notice side marker lamps, so if your asking about them, my best guess is that your car doesn't have them. The logic is that you don't know what you don't have.
If this helps--which it probally won't--here are the wire colors on the 69. It's a good chance that GM used the same colors on the 7's and 8's:
69 FIREBIRD
2 wires on L/R marker lamps: brown and black
parking/directional L/S: dk blue and brown R/S: brown and blk sgl/lt blue str (Whatever the hell that means. Heck! you don't think that they are going to make not confusing--do you?)
