the no# on the knock out is suppose to let the locksmith know how to cut the key to fit the door or ign. I think all the old 50s key blanks are the same, but don't bet on it (TRUE VALUE) stores always had the blanks for me and they still cut them the old fashion way. I'm sure older hardware stores should have them also. If you need a blank (orginal)for your truck and cant find one pm me and Ill send you some.
good luck,
Mike
