I just now noticed on my 96 w 92,000 a constant rattling noise. After lifting the hood and trying to pinpoint the source, I'm discouraged, because it seems to me to be coming from inside the engine, towards the rear. It is definitely engine related (and not drivetrain or wheels) because you can hear it in neutral, and it is modulated somewhat by the engine speed. It sounds a lot like my wife's subaru which has a loose exhaust shield, but after poking around in the enginge compartment and crawling underneath on a creeper with the engine running, this is not a shield.....I would have to swear it is something that sounds "loose" internal to the engine, and more towards the rear, transmission area than the front belts, alternator and compressor area. I tried turning the a'c on and off to see if that made a difference, but it seemed not to. Am I looking at a main bearing job or whatever its called?? Any help with this is appreciated.