RE: Whooshing - airleak sound from brakes
This won't help with your problem, but might easeyour concern a little. I bought a new 1988 Ranger S/C 4x4 XLT. It did the same thing. Sounded like air brakes releasing. Never did find out what it was,never had a problem with the brakes andI drove the truck for 14 years trouble free.
"Have a good day, and a better one tomorrow"