i have a 465 g with extra numbers stamped on the cases , matching letter/number on each half at the rear mount , it also has 7r stamped on one fork leg and 7g on the other , would this have been for a factory setup, perhaps gear shimming and case matching ? the barrell has had some work done to it , like the web between the transfers is about 3mm thick for a fair depth , and the ports appear to be matched up with the casting , it has a low production #, comments ??