Thread measurement for Air Pump to pulley

Anyone have an air pump laying around? Just purchased an 89 Bronco but need to modify to comply with California smog regulations. Previous owner did a smog pump delete. I have the parts (belt and pulley) but I need the thread measurement for the 3 screws that connect the pulley to the pump. Should I just remove the pump to get the exact measurement? Will eventually go that route if I can't find the specific measurement. Forgive me as this is my first post.