Pretty much.
Put your transmission and transfer case in neutral. Lift it one wheel at a time and try to spin them. If they free wheel then likely you don't have DT in the rear. Not sure how the front will work. If I remember correctly, with both fronts off the ground, spinning one wheel will spin both. Same in the rear.
I'm hoping to install my TT/DT from my 2000 into my 04 tomorrow if it doesn't rain to hard. I can let you know then.