LMC has an online catalog and on page 77 of their early Ford truck catalog is where you will find ignition parts. The cylinders, though not interchangeable between door and ignition, use the same tumblers. On the top of the cylinder there should be a rectangular hold down. If you gently pry it off the springs and tumblers can be pulled out or dropped out if you turn the cylinder over. If you take the hold down off be careful that you don't let the springs fly out as they are very small and easily lost. The tumblers are different lengths and correspond to the cuts in the key. If you can acquire a selection of tumblers you can re key any cylinder to match a specific key.