I had a '63 K10 when I was stationed at Luke AFB in the mid '90's and had good experiences with a company here in Phoenix called Grumpy's Truck Parts. They're also on the web. I now have a '63 C20 and a '66 Burb. I've been doing some prelim site surfing, magazine reading and came across Classic Performance Products. Prices look good, warranty looks good but have no personal experience buying from them yet. (lack of funds)