The majority of my whistling came from the driver's side rear view mirror. The TSB changes the mirror covers with a 3 ridge design into a new mirror cover. I don't have the TSB.
There is also a TSB for 2 model broncos (Big Bend, included) that produces a whistle from the grill/hood interaction. Regardless, the mirror cover TSB is the main issue; unfortunate that it did not solve it!
I just bought a Big Bend and have a Rigid light bar; I'm experiencing whistling. I know about the Tech Service Bulletin that Ford has out on the Big Bend and Outer Banks due to a whistling sound created by the design of the front grill and it's interaction with the hood. The brackets for the...