AC Adapter Identification for Latitude C840 and Latitude CPi?

I have two old Dell laptops and their AC Adapters, but neither adapter is identified as to which laptop it belongs and powers. The two Dell laptops are a Latitude C840 and a Latitude CPi: The two AC Adapters are: 1) Model ADP-70EB; PA-6 Family; P/N 9364AU, and 2) Model ADP-90FB Rev.B; PA-9 Family; and P/N 6G356.

I suspect the AC Adapter labeled PA-6 Family is the Latitude CPi because the PA number, PA-9 Family is a lower number...am I right or wrong. Need help, please.

Finally, why doesn't Dell put IDs on AC Adapter so we consumers know which laptop our AC Adapters belong.

Thanks folks!

Al