[rotorwrench]

Ford used that dark green on all 221 engines with a possible exception to the 41A replacement blocks beginning in late 1944. The early 1939 Mercury and truck 239 engines were still the dark green but had the 99 stamped to ID them at Ford plants in the USA. Canadian ones had a 99 casting number on them at least in the early 99A production. They later changed all the 239 engines to the dark blue color to more easily ID them during the vehicle assembly process. The blue stuck around till the end of the 59 era and on into the 8BA for a little while.

Ford changed colors in the 8BA era. 239 engines started out red in 1948 for truck production and all trucks remained that way till 1952 when they went green. The Ford cars started out dark blue in 1949 then changed to bronze in late 49 thru 51. They went tangerine or red in 52 & 53. Mercury 255 engine were green from 1949 thru 51 at least. I'm not as sure on the 52 & 53 Mercury cars Ford seemingly went to green on a lot of engines in those last two years of the flathead.