The Fond du Lac County Sheriff's Department says it has become the nation's first law enforcement agency to buy a $220,000 Oshkosh Corp. tactical vehicle that's based on a military truck used in the mountains of Afghanistan. The truck, which has an armored body and bulletproof windows, is designed for urban settings as well as off-road use, according to Oshkosh Corp., which has sought new markets for tactical vehicles as the war has ended in Iraq and winds down in Afghanistan.