Originally Posted by TreeSemdyZee

I mounted a wing on my 350 and what I did was attach thin mylar to the wing and traced the outside of the base and circled the screw holes. Then taped the mylar to the car and transferred the info to the car. I thought I had screwed up when I mounted the wing because the bolt holes didn't match up at first. When I tightened the bolts down, everything was perfect.
There was a little arc in the base, but that all tranferred properly when I taped the template flat to the car.
I was so excited when it worked that I literally looked very similar to this.
My neighbors probably thought I was crazy.

Thought this might help if you can't find a factory template.