Typically, you make a hole in the firewall (per the harness instructions) for the rubber grommet that the Mustang style EFI harness travels through. Then you usually have enough tail of the harness that the ECU will sit on the heater box. To the right of the ducts, closer to the Passenger kick panel.So if I'm understanding correctly.
If I have the ron Frances harness. Wherever I go through the firewall will directly affect how much "tail" i have and ultimately how i can avoid the defrost ducts?
I don't have ducts now so I guess I need to get them b4 I start. I already had someone do my paint and body and when they put it back together they got left out. I don't know if it was because my aftermarket gauges are in the way. ? I refigured my whole dash . I hate to buy ducts if I can use them. How much are they in the way?
The Explorer EFI harness's tail is a lot shorter, so you have to mount it in a box through the firewall if I am following you correctly.
Pic is the last RF Mustang EFI harness I did on a 77 Bronco...