General Motors Co. will restart vehicle assembly at its Spring Hill, Tenn., plant to build its hot-selling Chevrolet Equinox crossover. The Equinox currently is built only in Oshawa, Ontario, Canada, alongside its equally fast-selling GMC Terrain, but sales have outstripped the automaker’s ability to produce the vehicles. Through October, sales of the Equinox are up 23 percent for the year to date compared with the same period in 2010; Terrain sales are up 21 percent. Edmunds.com calculates the days-to-turn – the number of days from the vehicle being delivered to the dealership to being purchased by a consumer – is a meager 20 days for the Equinox and 24 days for the Terrain. Tennessee production of the Equinox begins in the second half of 2012.