Aïe !
I think I made an error, with the word "ochre" !
The 37 th BCC b1bis were olive green, with irregular DARK BROWN spots, like this one :
http://www.chars-francais.net/images/illlustrations/b1_bis_388_arlay_03.jpg
You can read that in the Pascal Danjou's book, Trackstory n°3.
It's a "poor" scheme (not many colors !) but the markings are a real challenge ;-)
By the way, the n°4 will deal with the R35/R40.