Here's a brief article from a June 2011 number of the NYT by Damien Cave detailing the bizarre improvised tanks used by Mexican drug gangs:
Over the weekend, Mexican authorities found two more of these makeshift road warriors in Tamaulipas, the same northern border state where the first armored vehicle appeared in April after a battle between the Gulf Cartel and the Zetas gang. In the latest case, the Mexican Defense Department said, the armored trucks were found in a metalworking shop in Camargo, which also held at least two other partly modified monsters and 23 additional trucks.
The completed versions were bigger than what has been found before. Built on three-axle truck beds, they had room for 20 armed men, one official said. They were covered with inch-thick steel, which could withstand 50-caliber fire, and each had been equipped with insulation.
(Image: a cropped thumbnail from an AP/Sedena image)