Jose
Here's the colour mixes for IDF Armour, I pulled down off that site (all Tamiya):
1956 Sinai War: XF62 Olive Drab
1967 6 Day War: 50% ea XF60 Dark Yellow & XF57 Buff
1973 Yom Kippur War: 33% ea XF59 Desert Yellow, XF57 Buff, XF20 Med Grey
1982 Lebanon War: 50% ea XF57 Buff, Xf20 Med Grey
current: MM's Israeli Sand Grey is pretty close.
Don't read too much into the photos. IDF Armour colours (esp the current one) is meant to absorb & reflect the light at setting sun such that the tank blends into the environment. I'm not certain, but I think this website might show some dusk photos with Merk's lurking: www.israeli-weapons.com In any case, if not totally convinced once the tank is painted, you could always run a wash of med grey over the entire model.
HTH
Shaun