1992 Nissan Truck help! I have no clue and really need you

I have a 1992 nissan D21 3.0L v-6. While I was going down the interstate it just quit like it was out of gas. When I got out to check it out the pulleys where spinning but nothing else and I have no clue what to check or what to buy in order to fix it. You can hear no internal parts moving but it looks as though the pulleys have little or no resistance on them. If u can help I would really apperciate it.

thank you