so there isn't a "last series" yet because it's still being made each year.
Here's the link to Panerai's website showing the PAM270 as a model in the Contemporary line-up: http://www.panerai.com/en/watch-collection/contemporary-collection/luminor-1950/61-10-days-gmt/71-luminor-1950-10-days-gmt-pam00270
Cheers,
Anthony
Panerai PAM270