I had a wonderful conversation with an old guy 30 years ago that was helping me restore two classics. He worked for Chevrolet division paint department. He told me the same thing that Tim said. At the time whichever jobber got the best low bid mixed the engine paint by there eye. Therefore both the blue and grey were varied. The color of grey was called dove grey according to him. Tim, I believe has an article regarding your question. The end result is it is great for us because we don't have to be ruled by an exact shade. Take it from a guy that painted his 54-3100 engine blue. Apparently the cars were blue trucks grey. Doc.
