1985 GPZ550 Carb Rebuild Kit Request

Great eye! I had no idea there was even anything stamped there! Here is as good of a pic as my phone will allow. 1979 4I05 (the ‘I’ being a capital i). 

Thank you for that. As I understand it the id the 85 GPZ 550 according to partizilla is as follows: 
for the us 16001-1974
for canada 16001-1979

The pic you posted appears to be showing 1979 which in my thoughts makes them the canada version, I am not sure if there are any internal differences between the 2 part numbers.
 

I have felt for a long time that just about all of the carbs that came stock on the Kaws from the mid 70s certainly through the mid to late 80s have an ID stamped on them somewhere. Am I saying all, NO, I am not but IMO most do have an ID stamped on them. Many appear to be what I call the secondary part number, of the  Kaw carb assembly  part #. But what do I know?