From the oldGMCtrucks.com discussion board:

SlmSix (Andy from MN):

Quote
So with the help of K10 I have come up with what I believe to be the correct "olive" green paint color for the 1939-1950 GMC 6 cylinder engines. Pete was kind enough to send me a flywheel cover off his original 228 that used to live in his '45 pickup. He replaced the original 1945 228 at one point with another 228 and painted the replacement engine using green paint that was computer matched off of the 1945 228. The paint he used was a Centari brand put into rattle cans which is no longer readily available. The local store for me uses PPG products and they can put acrylic enamel in spray cans. So I went and asked them if they could cross the Centari formula to a PPG equivalent. No go. However, looking through the PPG Fleet color chip books they had on the counter, I found a nice selection of olive green paints. I compared them to Pete's flywheel cover and got lucky! The PPG 45244 Beechcraft Olive Green was just about perfect!