I have gone through this numerous times, OEM mount and inlet/exhaust is for OEM heaters, designed for the Air Top 3500 suitable for 3500, 3500ST, Evo 3900, Evo 40, Evo 5500 and Evo 55. They line up perfectly with OEM ducts.
You were contacting me about the kit that I had for sale both here and on Ebay but did nothing but dither about.
All the information is in the threads.
I can only hold your hand so much!