If you have the original hood, and it looks like the replacement letters have studs. They are probably held on by 'Speed Nuts'. springy square tabs that have a friction connection. You have to pry them off, they are usually re-useable. When you get the old ones off clean all the gunk off where they were, then the new ones should just pop into the existing holes and then slide on the speed nuts. There are a couple of related threads above where the replacement hoods were not pre- drilled.