I'm looking for some help confirming the identification of a pair of old Buffet Crampon clarinets that have recently come my way.  Based on the history of the instruments, I believe they were likely purchased in the 1950s.  The serial numbers start with "52" and are five numbers long.  They are beautiful, well-loved, wood instruments that I suspect may be R13 models from perhaps one of the first years of production in the mid-1950s, but I'm hoping to learn more about what I have on my hands.  Any help is appreciated!