Maybe someone out there has heard of this. I have a 2003 'Wing, 39,000 miles on the clock. The other day while riding to work, a loud rattling noise started to occur at low idle. Put the trans in first gear and let the clutch out slightly while holding the brake to load the drive train and the there is no change in the noise as long as the rpms stay at low idle speed, about 500-600 rpm. Raise the rpms above 800 rpm and the noise goes away completely, in neutral or in gear. I accelerated at full throttle through the gears, no noise, normal power and performance. No oil light at low idle when this noise occurs, so I don't think it's main or rod bearings. Since the noise doesn't change when the drivetrain is loaded or in neutral, I don't think it's in the trans or final drive. We've all heard this noise before, it's the same exact noise you get when you turn a corner and try to accelerate in too tall a gear and the engine lugs, THAT noise, only mine now does it in neutral at warm idle. I mean it vibrates the whole frame! Ran over the whole engine/trans casing with a stethescope and it seems to be coming from the alternator/waterpump/starter/reverse gear housing. Started the long process of teardown today and am pretty sure that's where I'll find the problem, but I would appreciate any insight from anyone who may have had experience with this already. If you want to just make general comments please make them here. If you have real and valuable advice for me, please email me at [email protected]. Thanks in advance for some real help!