My apologies if I misunderstood your question. My plastic pan does not attach like the one shown in the PET. I have three bolts which go through both the trailing edge of the "batwing (front apron)" and the front of the plastic pan, and they fit into nuts that are welded to the back of the radiator support. There are no "captive nuts" (part #4) for my car.
I do have captive nuts in the front/middle of the pan, but they have never been attached to anything - I will check tonight to see if they attach to something as mentioned earlier in this thread.
There are then also three speed nuts and bolts to attach the rear of the plastic pan to the front of the metal pan if it's there.