Workers have mostly enclosed the 335,000-square-foot addition at Chrysler Group LLC's Toledo Assembly complex. The work is part of a $500 million investment Chrysler announced for the plant in November. The expanded line will build Chrysler's replacement for the Jeep Liberty, production of which is set to end this summer. Chrysler intends to add a second shift and hire 1,100 employees for the plant, which could build six different vehicles. Chrysler hasn't announced when the expansion will be finished.