Usually only ever 3 shanked threaded screws hold the NORMMALLY.. radiator support and mounted regulator in place.

THE RUBBERS listed go under the regulator to help INSULATE from vibration.

NOT ORDINARY SCREWS..

REMEMBER or be aware.... this era regular has  INSULATED MOUNTINGS....for a reason.. to reduce vibration... so don't do what a few people have done & fasten them metal to metal onto the radiator support panel.. then FRY the regulator.

External regulators are NOT used on cars with an Alternator that has an internal regulator.