Guys, headed out for the weekend. If nobody replies and you need these dims quickly, I can only tell you the dims I used have over 3000 miles on them without incident. Suspension in use is not relevant. These dims won't change regardless.
If you want to come up with your own dims, you want to mount the new drivers dead center between the existing drivers....
You can confirm driver center to center using dims derived from the window openings in the track itself. Hope this helps! FWIW