YES you most certainly can. I had one on my old 98 GT. The factory supplied oil sending unit indicator only warns you once the oil in your car is less than 5%, basically meaning kiss your engine goodbye warning. It is hooked up the same way on GTs as it is on GTPs.
Both model cars have the same 3800 series block, so the opening is located right above the passanger side driver axel at the end of the tranny. The Original sensor is GREEN in color, so it should not be hard to find.
I hope that helps