Vicious 88 GTA

I started crusing around tonite and heard this loud grinding noise and stopped at my GF's house and it was horrible, so I got in my car and it kept going then I reved to about 2200RPM and it stopped, ahhh ok alls good...or so I think....I get to my cousins house and I hear the engine like overheating and guess what!!! there was no alternator pulley!!! it fell off as well as the belt....and now I don't know what to do, I found the pulley, it was back at my GF's house, is there like a cotter pin that goes connected to bearing or something...I dont understand how if fell off, it grinded alot thought...thanks...AARON

Justins86bird

The alt pulley is held on by a nut.