The dark green is the standard color and most the trucks are painted that color. And its not just the big bolts, its all the big GM trucks.
Most of GM's records where lost 50 years ago, but even then much of what you want to know was not kept. It wasn't like today when every detail is stored away in a computer.
You'll find model number and wheelbase length in the
Restoration Packs.
If you are serious about restoration data you'll want to become familiar with these pages.