Tom,
The IDF's main tank is the Merkava. They started with the I series in the early 80s and are now up to the IV series. Each series has its own upgrades, so you will see IIB, IIC, IIIC, IIID, etc. They usually involve adding different armor packages.
The Magach tanks are modified M-60 tanks. The most common ones these days are the 7A and 7C. The hulls have added armor and side skirts. The turrets look completely different, with new armor sections added to the turret.
The M-113 is still used, in many versions. APC upgrades include the Zelda and Nagman.
The IDF also uses an APC called the Achzarit, which uses a T-55 hull and new armored top section.
The Tamiya kit is fine for the Merkava I. Academy makes a good Merkava II. Academy's Merkava III is based on the prototype and is not accurate. Legends makes great conversions for the Academy kit, they have a IIIC and IIID conversion.
Legend also makes conversions for the Magach 7A and 7C. I believe you can use any of the M-60 models for the conversions.
The best M-113s are the Academy series. Blast models (http://www.blast-models.com/) makes conversions for the Nagman APC, and Legends makes conversions for the Zelda and other series.
Legend also makes an Achzarit conversion for the T-55 model.
You can see photos of these at
http://www.waronline.org/IDF/photodir_en.php?dir=Army.Osprey has a great book that explains all the conversions the IDF has done in the last 20 years.
http://www.ospreypublishing.com/title_detail.php/title=S5791~ser=NVG~per=6Hope it helps, let me know if you have any other questions.
How can you get Legends stuff so cheaply?
Dave