Benhicksphot-
Man, my coach has so many penetrations that I could skip the vent system!
The Ford F-53 chassis has some pretty big wire bundles for the coach builder to get into the cab.
Your Winnie's wiring diagrams are available at
this link. in particular, the "Front End Wiring Installation" is at
this link, and give ideas as to where the penetrations are. This may not be the only diagram that has the information you seek. For instance, the "
Chassis Wiring Installation" set, sheet 3, shows the front end.