Bakula is 6'0". Trinneer has said he stands just under 5'11".
Camera angle and posture (or standing on sand, as in DC) can affect the perceived height of actors.
Jolene Blalock, who is 5'5", wore heels on the show. And she was often put on an apple box in close-ups with Bakula or Trinneer to give her some artificial "height" in order to facilitate better camera angles.
walking shot - accurate height difference
static close-up: less height difference