When I started my car yesyerday I heard a strange noise under the hood. Upon further inspection, I noticed that the nut had come off of the alternator pulley and the pulley was about to come off. I don't have any idea where it's at. Can I just get one at a hardware store or is this some kind of odd thread size. Thanks for the help.

 

Hardware store.

 

you'll either need an impact to put it on or something to hold the pulley