Thor Industries Inc. has announced plans to expand its northern Indiana operations of recreation vehicle manufacturer Jayco and create more than 300 new jobs. The announced the expansion of more than 400,000 square feet in Middlebury is due to the growing demand for Jayco's travel trailers, fifth wheels, toy haulers and motorhomes. The expansion about 30 miles east of South Bend includes two manufacturing plants, including one that's expected to begin operations in early February and add about 200 jobs. The second plant is expected to begin operations by mid-June.