How would i know if someone put them on my car?

 

I would measure them. I am not sure of the size of the stock pullies, but I am sur esomeone on here knows the dimensions. Or you could always Google it. I was courious about mine also. The guy I got it from said they were on, but they look like stock Ford pullies to me.

 

The crank pulley will be smaller than your harmonic balancer, like this...

 

Looks like I do have UD pullies. Only mine must have been the first ones ever produced. Not as pretty as pro50sc's.