geddy lee

I received my black and silver license plate to take the place of the crummy blue and gold plate ( Delaware ). It should look really good on my 2009 Magnetic Black. Does anyone know the bolt size ( thread type )? I believe the bolt head takes a 3/8 " socket but they are really seized up and I know I'll probably end up breaking them or stripping something and have to get new ones, preferably stainless steel. Thanks