Tom's Baja: Heater Blower
I removed that Y piece that normally sends some air under the driver seat. The arrow and little white marks show where there is a 90 degreen turn between the fan outlet and the rear of the heater channel. I no longer have heat in the rear footwell. Being selfish, I want all the heat up front.
The large pipe is from a heating/air conditioning supplier. Inexpensive. Cut at an angle to fit the inlet of the bus blower fan.