Alan
I have the Osprey book "US Marines Corps Tanks of World War II" by Steven J. Zaloga. In it there is a color plate of a M4A2 from Company B Marine 4th Tank Batalion with a yellow turret top. the caption notes that the yellow paint was more durable than the red and yello air identification panels. Some tanks also had thire number painted in large numbers on top of the turret too.