From “End Game” (S2E17), Mulder uses a handheld GPS. It looks to be a Magellan brand unit. Consumer GPS was still very rare in 1995, and selective availability was still in effect, so GPS accuracy was still ~100 meters.
The display shows real coordinates which actually plots to the Beaufort Sea which is exactly where the episode takes place.
Something I never would have picked up on before, the date displayed “03Feb95” seems to be the original air date.