I guessed what you were looking at after seeing the Feedback thread.
Picture isn't that great, even in the large version on Amazon, but it does look like there is something standing up to about the level of the co-driver's hatch. Time to look some more

As for colours, Shermans came in US Olive Drab and if they got repainted it was with SCC15, which is a similar colour, but more green.
David