It's fixed, but I thought I'd share this...I have a 97 Olds Bravada (Jimmy/Blazer). Ever since we got it in 99 it has made this strange gurgling noise from the glove box. It turned out to be the heater core having a small hole that wasn't letting water out but letting air in. The air getting in to the system destroyed the DexCool crap I had in there, causing lots of other problems (radiator, waterpump). Eventually the pinhole got big enough that it leaked and that was when I found it. SO for those of you with a gurgling vehicle...
The funny thing is I took it to the Olds dealership a few times to get the noise checked out and they said it was normal, even after they replaced the cooling system (except for the heater core) twice.