I am wanting to get a 1955 Chevy 6400 with the 261 motor. It has been in a field for about 10+ years and the keys to it that were left in there when parked are gone. I guess mice like shiny things that rattle! There are no door locks, just a glovebox lock and ignition. I have been told I can get the glovebox and ignition lock cylinders for about $10-$20, but not told where to get them. I have found a classic GM website and for 2 door lock cylinders, a glovebox lock, and an ignition, it is $50+Shipping. The story and plans for this truck are on my profile posts and it is called, "Fixing the Family Truck". Anything is helpful.
