If no one else gets you an answer, I'll see what my dad can find out when he goes to work tomorrow... hopefully Deltas systems will let him check past schedules... any idea what year you went/what month even if possible? Might help him.
When I flew to Athens on Delta we flew from Orlando to Frankfurt on an L-1011 and then on a DL 727-200 from FRA- ATH. That was in March of 1993. I would assume that any L-1011 flights directly into ATH on DL would have been after that.