You didn't mention what version of the Merkava the kit is. If it's a Mk 3, here are some photos:
http://krimi.tripod.com/merk3baz/merk3baz.html
I used Testors MM Acrylic "Israeli Armor Sand Gray"-It doesn't match the color in these pictures, but it might be good for some older vehicles. It's kind of a greenish-sand, if that makes sense...