2015's only had 5 digits for the chassis numbers and it is my understanding that the R models did not have an "R" included in the chassis number.Max's found
2015 GT350's - known caps
2016 GT350's - not sure, but I know they made at least 5,505 regular ones...
2017 GT350's - wonder if they're going to keep pace of 5000+/500, since they're sitting on showrooms unlike last year when they couldn't keep them in stock.
I could be wrong but I thought the chassis numbers were "F0001 to F0037" for the 37 R models and from "F0038 to F0137" being the 50 Track and 50 Tech Pack car chassis numbers.
With respect to the 2016 cars I believe that "GR499" was the last R model built for the 2016MY. Keep in mind there were at least a couple of R models built such as "G0089" and G0091" that didn't have an "R" in the chassis number so that may change the total number of R's built.
Don't know much about the regular 2016 GT350 cars but looks like what you have listed for the regular cars as possibly being the last one built.
We can only speculate on the 2017MY production numbers but suggest much the same as 2016 but we all may be surprised by some different production numbers for either the regular cars or the R models.