Specifically, I don't know if the fenders are the same. However, it was between 73 and 74 that there were major changes so the Mustang II and the Pinto could share aspects.
My guess would be that the 72 and 73 fenders are likely the same. The major difference between the 72 and 73 as far as I know was the forward extension of, and support behind the front bumper. So, the rubbery piece between the lower end of the grill and the upper part of the bumper I believe is longer. Off the top of my head I'm thinking if anything was different it might be side marker lenses.
All that side Ford seems to be famous for changing things for no obvious reason. The 73 Pinto's has a one year only steering rack. The 71-73 Pinto's had a different front suspension (and rotors). The wagons have longer rear springs and shocks.