Chinook RV

The new unit should run cooler than the old one, but that's probably because there are two fans. Definitely make sure there is an opening in the shell for each fan. Here is a picture of the Progressive Dynamics shell with the board inside.

I was finally able to install the PD4645. (Thanks Clay).
I called Progressive Dynamics to ask about using the old box.
They told me that the box is designed for proper airflow, and that it would be better to use the proper one, even though the old one would work somewhat if I cut more holes in it.
Still, it was lying flat on the bottom with no relief for air, so I got a new box.
It is working very well now.

Nothing beats the peace of mind when the OEM says that it is the right setup. I hope the enclosure did not set you back much, but I do think Progressive Dynamics is not going to ask for your first born.