green or black, what's the difference?

I have a 5/77 280. What is the difference between the black or green base on the cold start valve? I know the 75-77 models use the same cold start valves and the 78-83 use a different one. which one is which? I am putting my z's f.i. system back on now (restoring) and for some reason I can't remember which on is correct. I have both green and black and don't remember which one was on my intake. I have everything else bagged and tagged except this! Your help is appreciated.

Bob