QUOTE(The Cabinetmaker @ May 31 2017, 12:39 PM)
It is part of the Plenum
Good question but I don't know.
Its either part of the plenum or it mounts to one of the case bolts. I thought it mounted to the case bolt but I haven't been able to find a parts break-down online. Actually I did find it on AA's website on a parts break-down but it wasn't clear to me how it mounted. I figured I'd figure that out when I got it.
Now that you mention it I did take photos as I took it all apart. I'll have to look back and see if I captured that.
Thanks
Steve