'65 C10 blower resistor location

[jmcap]

Hi Guys,

Helping my son get his old truck up to snuff. Just ordered a new heater wiring harness and resistor.  It's a Deluxe model. Bench tested the motor it's fine.  Under the dash is a nightmare. Correct me if I'm wrong but I believe the resistor mounts to an opening in the air box.  Here in lies my confusion.  There appears to be a rectangular patch over what I assume was an opening located pretty far up the box on the passenger side.  As well there is another opening just to the left of the passenger's floor vent.  It's a larger rectangle.  Anyone have a picture to share of the resistor mounted as well as the ducts for the driver's floor side and defroster ?