I cannot recall the size of the plugs to tell you the truth. The big one that the actual motor comes through is about the size of your hood heat shield. It needs that much surface area to cover that big hole on the outside.
I grabbed a bunch of other different sizes, tried them out, had the plastic speed nuts on the inside, color matched them and gooped it with some black silicone underneath the cap on the outside and plenty on the inside. Have not had any leaking issues and the paint is still holding up nicely.
Did the same thing with my OnStar shark fin.
I know not as smooth as Red Rocket's lift gate, but I am still happy it is gone every day I look at it. Until I can get it properly shaved, it still looks badass and the average person will not even notice the plugs or that you even had a wiper there in the first place.
@95escahoe