River Valley Co-op has identified the former Fedor Pontiac Oldsmobile property on Route 10 as the best spot for its second location. The grocery cooperative announced Monday that it has an option agreement to purchase the property at 228 Northampton St. from the Fedor family. The price was not disclosed. The dealership is vacant, having closed in 2010 when General Motors downsized its dealer network and ended the Pontiac brand during the automaker’s post-recession bankruptcy. Oldsmobile went out of production in 2004.