I think this is the apropriate section:

c. The entire rear wing assembly, including the end plates and
any wicker, shall be mounted a minimum of 6.0 inches below
the peak of the roof
or roll cage main hoop whichever is higher,
measured at the highest point. Cars with a wagonback/notchback/
hatchback style body may have the rear wing assembly,
including the end plates and any wicker, mounted a maximum
of 4.0 inches above the highest point of the roof. For this
subsection, a wagonback/notchback/hatchback style body
(or variations of these) is a car in which the rear edge of the
roofline is no more than 28.0 inches forward of the rearmost

bodywork as measured along the vehicle longitudinal centerline.