Last run metrics from _old_ versions of puppet.

Backstory: We have a totally fragmented system, and are running a number of really ancient versions of puppet. There are apparently reasons not to upgrade these instances. We have some 2.6.4, some 2.6.9, some 2.6.17, some 3.7.4. We are looking for a way to universally monitor a few key metrics from them all. I wrote a datadog check in python to read the /var/lib/puppet/state/last_run_summary.yaml file to extract some of this information. Turns out 2.6.4 doesn't write this file. The question: Does anyone know of another way to return the last puppet run date, and the number of failures? Are there command line options for puppet that span some or all of these versions of puppet that might work for me? Any other files that might allow me to parse this information? Huge thanks in advance! Peter