Tanker's Tuesday: Merkava Mk. 4

During the Merkava Mk. 3's years of production, a number of modifications have been introduced, the major ones being a modern fire control system with an automatic target tracker ("Baz") and significant improvements in ballistic protection. 

The production of the Merkava Mk. 3 lasted until 2002, whereupon the Merkava Mk. 4 was first fielded to the Armor Corp.

http://www.israeli-weapons.com/weapons/vehicles/tanks/merkava/MerkavaMk4.html