Oops, forgot to add 2 things:
1) the wing pictured was installed by my car's previous owner so, I am not sure about the answers to your spec / thread questions (not trying to be 'obtuse' mind you); and,
2) NOTE: the car's previous owner is a machinist by trade and I will never forget him telling me that, had he followed the directions included, "to the letter" that the wing would have wound up 3 to 5/8" off center.
I just remember him saying over and over how thankful he was that he had trusted his own abilities to measure twice in order to drill metal just once, over whatever directions came with the wing.
(And, I also remember me thinking at the same time, "
Geez, if he hadn't already installed this wing, I wonder who a big chicken like me would get to do it?"