I don't know what kind of bus Michael Wagner is trying to aerate, but for
non-sunroof vans, the aftermarket sunroof I put in my 81 Vgon was a real
good $90 investment.  Left open when you park, it keeps the car cooler,
and it helps move air thru while you drive, more quietly than opening any
window.  I put it over the second seat, not in front where it lets sun
shine on the driver and front passenger.  The handle is just in reach
from the driver's seat.  Toughest part of installation is getting the
headliner tucked in neatly around the sunroof, altho' cutting the roof
takes the most courage.
B.

Wm Kennedy