I've got an issue going on with my '99 obs K1500. I recently replaced the radiator (after some stop leak didn't fix the leak). I let the truck run as I was filling the radiator, but it didn't take very long for the the bubbles to stop coming out, so I thought it purged all the air out. Now I get what sounds like water sloshing around under the dash on the passenger side. It only does it under acceleration. I'm not sure what's the best way to remedy this