GM Adding Third Shift to Build Midsize Pickups By Jason Siu Sep 16 2014 Share this Article Tweet General Motors is investing in its Wentzville assembly plant to prepare for its new midsize pickups. Continue Reading... Filed under: American Chevrolet Featured Articles GM GMC TrucksTags: canyon, canyon demand, canyon production, Chevrolet Colorado, chevy, chevy colorado, colorado, colorado demand, colorado production, gmc canyon, wentzville assembly plant, wentzville plant