Wikipedia claims that the F-4 Phantom is still in use by Iran, Japan, South Korea, and Turkey. Turkey were certainly using them last year to bomb Kurds. So that's 1958 - 2016 at least - a respectable innings!
A-nis bidh fios aig daoine nuair a tha mi a 'mionnachadh aig dhaibh.
Well, if S.Korea is using them, we might get to see some in action soon. "alongside South Korean F-15K Slam Eagles and F-4 Phantom IIs during the wargame under realistic wartime conditions"
There are apparently still four Ju-52 in regular passenger-carrying operation, although not military use. If that counts, then that'd take some beating.
Junkers Ju-52 wrote: 1930 - present
A-nis bidh fios aig daoine nuair a tha mi a 'mionnachadh aig dhaibh.