DVAP is out there. Desert Valley auto parts. there are several apparently, including one in Casa Grande. See link below and view the small video on their intro page. They have many GM trucks in the "Survivor" category on the website.
But if your into GM trucks, you should go see Patrick's, which is also in Casa Grande. I went there in '04 during a Barrett Jackson auction week and met Patrick and his wife and his son Philip who both work with him. He showed us his operations including his used truck stockpiles as well as his remanufacturing facility for remaking 47-54 GM trucks. He also bought us lunch and we ate in his shipping department. You won't find a nicer guy. he has his opinions, well earned over many decades in the business, but he knows his stuff as well.
http://www.dvap.comhttp://www.patricksantiquecars.com/chevrolet.htm
