Numbers on Improved Gramophones

[pappde]

I would like to know more about the numbers on Berliner TM machines.
First off the engraving on the spring housing. When did the J appear above the number? At what time did they start putting on the patent info above the numbers? Is there any relation between the number and time of manufacture?
Second, on the Clark-Johnson soundbox what was the highest known number? I have seen a picture of a CJ with 60K number. Were the "export" sound boxes numbered differently?
Third, was there any relationship between the two numbers?
Thanks: Denes