As usual this is another case of documenting what your car originally had... I've seen at least 2 mabe 3 studs per side on the top and at least 1 but commonly 2 studs on the fender bottom...It all comes down to the assembly line installer and the crisis of the day... The studs made hanging the fender much easier hence the reason for using them but any combo of bolts and/or studs would have been possible...Here we are 40-50 years later and the resto community has drawn conclusions as to what's "correct" in the name of selling kits to make it easy...