I am by no means an expert on the subject of IDF colors, but I have done quite a bit of research on the internet over the years. Depending on what specific Centurion you are building (that is, Sho't for the early Meteor engined version or Sho't Kal for the later Continental engined version), as well as what time period (1967 war era, 1973 war era), the colors are different. The below is a link to some ideas for colors for various periods, and covers Lifecolor, Tamiya and Humbrol paints. I am in the middle of building the AFV Club 1967 Sho't. I use Tamiya paints almost exclusively (unless I an find a premix for a given color, then I may use a different paint manufacturer). For my Sho't, I am using the 50/50 Dark Yellow/Buff mixture. If you go this route, as another prior poster suggested, you'll find that this mixture gives you a distinctly 'dark mustard yellow' color. I'm not saying that the link represents complete color accuracy, but it gives you some options.
Not that you were asking for this, (and I'm not trying to contradict any other posters on this thread) but the Humbrol 84 is a good representation of the modern IDF color, or the Tamiya mixtures that closely duplicate that Humbrol color. This would not apply, of course, to your IDF Centurion.
Hope this helps. If you need more clarification, please ask.http://idfmodelling.free.fr/article01.html