Bobby said "You will find very few A/C units with a drip pan.
The Dometic Duo-Therm Penguin is available with or without the drip pan.
You will want the drip pan. The roof opening will stay the same size.
If you don't want to mess with it take it to Walt Barksdale in Ocala.
If you need his number let me know and I'll get it for you."
Pete,
We can second that recommendation. Walt installed a Dometic on our '83
after 3 years of our babying and fixing the old one. The drip pan comes
from Airstream who told us Coleman changed the bolt arrangement so they
only make one that fits Dometic.
You really don't want that water dripping down the side. While we were
at Port O Call in Melbourne we saw many with the water going over the
side and the aluminum looked terrible.
Tricia & Conrad