Since the bronco has the gas tank in the rear it could get a true dual exhaust,since the crown vics could come with a true dual exhaust they have dual O2 sensors so I was thinking about using the EFI harness from a crown vic in my bronco so when its gets duals the EFI will work right. Anybody ever do something like this.

 

I would not do it. I would keep all my original Bronco wiring and computer, run the duals if you want, and just put the oxygen sensor to read one side of the engine. I did a search, there are a lot of people who do this and have no trouble out of it.