easiest way is to look at the headlights / front end
98-2001
2001.5 +
2001.5 does not have the rubstrip that carries across the front end of the car like the earlier version does.
the angle of the front corner lights on the side of the car is more vertical on the 2001- cars... and angled down and to the back, on the 2001.5 cars
2001.5 will have chrome around the windows, and as an integral part of the side molding/rub strips... whereas the older ones do not.