congrats on the new ride. u can tell if its the stock pulley but lookin or measuring. if its stock it will be 8.5in in diameter and have an aluminum looking center with the rest of the pulley lookin black. the stock one will have ford stamped on it. hope this helps

 

I don't have a picture to post. But the stock lower will have a cage over it. Some aftermarket lowers also have the cage but many do not. That will give you at least a sign. I do believe the factory cage has ford stameped in it also.

Also, another indicator may be the size of the belt itself. Most guys bust off a little tab on the tensioner to give it more range to get the belt on an aftermarket lower. Sorry I can't be more descriptive but maybe someone here can post a pic for you.

 

Very Nice!!!! Wish I would havent gotten one