I'm trying to locate where the truck takes in the air for the air plenum. I'm wondering this because I have an exhaust smell coming inside the cab. I've done the dreaded manifold replacement on both sides.My truck is a 2007 FX4 Crew Cab with the 5.4. Thanks in advance for all the help.

 

You mean for the heater? The inlet is in the cowl between the windshield and hood.

Is your exhaust stock or is it dumped under the truck?

 

Yeah the heater is what I'm talking about. I have stock exhaust that exits out behind the tire on the passenger side.