You need 7" behind the shutter!
Your review: You will need 7" behind the shutter to install the motor kit, so they can't be installed next to the fan. We built a 7-1/2" box around the fan to get the room with standard 2x8's. They are also noisy and sound like they will burn out while holding the shutter open, but you usually can't hear it over the fan. I hope they last!