I assume it is dark green, but I prefer to have more specific information.
For ground vehicles? FS# 34052.
note: it was not uncommon to see Marine armor taken from Army stocks in combat, and thus the darker O.D. that the Army used. I’ve seen M48’s with parts taken from CBL’d tracks piled up in the major repair facility that were from Army tracks and I’ve seen Army tracks with Marine parts. Everybody cabbaged parts off that pile of scrap iron. Parts shortages were the norm