IIRC, the Germans, French, Dutch and Belgians had all agreed to be using the same paint (RAL 6014 – Yellow Olive), but either the batches varied or the photography of the time is misleading, because the Dutch and Belgians (which match each other) seemed to be using a distinctly more dark grey-green shade than the French and Germans; more akin to the Forest Green used by the US Army during that period (i.e. the green colour used in Winter Temperate MERDC camouflage or plain on Abrams and Bradleys delivered to Germany during the 80s).
The West German and French colours seem to match very closely, with the French possibly erring to the brown end of the colour-range, so I’d use whatever colour you’d use for West Germans. The Flames of War/Team Yankee chaps recommend Vallejo 321 Cobra Drab. I use Humbrol 155 US OD.
Re Honourable Exceptions: The Danes also used a green/black scheme similar to the British, though with slightly more black coverage and with a much brighter green. Sadly I went a bit ‘dull’ with my Danes and should have done a brighter green more akin to my West German helicopters (see my recent battle report). Norway also used an epic splinter camo scheme, but it’s presumably a right sod to paint.
My wargames blog: http://www.jemimafawr.co.uk/