I'm in possession of a model 64-4 with a 2" barrel in .38 special. For some dark reason, the serialnumber in the bottom of the butt has been made deliberately unreadable. It has, I think, 7 digits. On the yoke, there are 3 digits (034, eventually O34). On the right hand side of the buttframe, there are 7 digits (7816 034 or O34) Is this also the original serialnumber of the gun an if so, can somebody date the period of construction of the gun?