APC's
One of the lessons learned so costly at the Yom Kippur and Lebanon wars was the vulnerability of the armored personnel carrier (APC) in the modern battlefield. In the battle of Buq'atta (1973), for example, most of the 7th Recon Co was wiped out while trying to assault Syrian Commandos with their M-113's.
The situation in southern Lebanon - where Hizbulla guerrillas ambush Israeli APC's and IFV's with ATGM's, mines and AT charges, also called for an improvement in APC armor.
M-113
Since 1973, the M-113 is the main APC in IDF service. However, it proved as totally inadequate for direct fighting, due to it's poor armor protection. The Israeli army introduced many improvements to the basic design (such as taking the main fuel tank out of the vehicle) and to the armor.
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Achzarit
The Achzarit (Hebrew for "cruel woman"...) is an original Israeli APC. The Achzarit is actually a T-54 or T-55 MBT, which the IDF had captured by the hundred in the 1967 and 1973 wars. The turret was removed, and accommodation for troops was added. The Achzarit is probably one of the world's best armored APC's.
By the way, the Russian Army has recently adopted the Achzarit model - and it is now converting T-55 and T-54 tanks to the BTR-T APC.
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Puma
Another example of a MBT converted to APC. Sh'ot (Centurion) tanks were converted to armored personnel carriers for the Israeli Combat Engineer Corps. The Puma's role is to provide protection and fire support for the Engineers as they clear paths through minefields.
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Puma APC with Israeli Engineers in Southern Lebanon