a standard gt reverso duo in gold (hence 1.54.. mine in steel is 8.54, rose gold seems to be 2.54). 25x case prefix is traditional classique.
Later ones should have the 1000hrs and fish logo to rear of cradle, and pusher that isn’t recessed, along with round sub seconds (think I’m recalling that right)
Earlier ones have recessed pusher (not that awkward), square sub seconds. May find with either single bifold or duofold buckle if not braceleted.. later ones
tend to have the duofold.
.. as you’ve already figured - about 15-20 years ..