Yeah they are talking about the vacuum that gets pulled to assists the brakes, essentially it's where "power brakes" came from. the old school cars had non power brakes and you really need to press on them. Why am I talking about the brakes? Because another poster said that he heard the noise come from over at the brake booster and the brake booster needs a vacuum hence that's where this is going.
Anyway, if I were a gambling man I'd bet you will still get the squeal eventually, please keep us posted to see how it goes.
yes they want me to start it up with them listening to make sure it still doesn't produce noise but i will watch it close and if it does who knows may just live with it or try to have it taken back under lemon law. i really do love this jeep (1st one)