Yeah, I was thinking about that. I will get a stud finder and try and
center the fan between 2 joists. Then I'll cut the hole the size of
my box. Then I'll go up to measure and cut a 2x4 to fit between the
joists.

I am just finishing up painting 7 rooms, so we have tons of tarps and
plastic around. Depending on how much insulation comes down I was
thinking about either going up and clearing away as much as possible
before I cut my hole and/or shopvac'ing up the bit that comes down and
throwing it back up in the attic.

Thanks for your help.