Most workers at the General Motors Bowling Green Assembly Plant are on an extended vacation that started July 28, as the plant is reworked in preparation for manufacturing 2018 models of the Corvette.Speaking last week during the Corvette plant’s awarding of grants to local nonprofit organizations, Plant Manager Kai Spande said July 28 will be the last work day before the shutdown starts. It will last 13 weeks, he said.The extended shutdown is for equipment installation, setting up the new car build process for the 2018 Corvette and finishing construction of the nearly $500 million paint shop announced in 2015. Spande said the total cost of reworking the plant comes to nearly $900 million.Jack Bowers, vice president of United Auto Workers Local 2164 in Bowling Green, said certain areas of the plant, “mostly painters,” will continue to work during the 13 weeks. But the majority of the plant’s workers will use vacation time and draw unemployment benefits until the plant reopens in October, Bowers said.Bowers expects the plant’s 838 permanent employees to return to work in October, but he said the temporary workers would not come back right away. The plant has several hundred temporary workers.“It will be a slow, steady process when you do this level of restructuring in the plant,” Bowers said. “We’re basically rearranging things so that parts coming from the paint area are coming from a different area, and we’ll be using a conveyor system to bring all parts over to be assembled. It will take at least a month to get things rolling.”Spande said 2018 Corvettes should start rolling out in November. Based on incentives granted to GM last year, employment at the Corvette plant could increase after the reopening.The Kentucky Economic Development Finance Authority approved GM for up to $3 million in tax incentives through the Kentucky Business Investment program. The incentives are based on eligible company investments of up to $153 million.