"Rich Greenberg" ...
Tomes :

So the advice here is to just replace the guts inside the box and not
use
the new box that comes with the new assembly. Hmmm. I am thinking that
the new stuff really wants to use the new box as it is already all put
together and all. I'll take another look at the stuff and consider
this.
Thanks for a thought that I had not considered yet.

The reason it comes complete with a box is to allow for the same
fan/light package to be used in both new and replacement installations.

I see our disconnect here. You are envisioning a light/fan that is in a
regular room. I mean one that is in the bathroom with an exhaust fan.
Thanks anyway, Rich, much appreciated.
Tomes