I just heard this grating noise (like two steel plates rubbing against each other) coming from the gear box area today. It increases in loudness as the rpms go up. The shifting feels good however. I just got an engine rebuild and this is the first time I was driving with my windows closed. When there open I can hardly hear it. Today the mechanic had to drop the transmission again to fix the main gasket. I have a lightened flywheel. Could the flywheel be making grinding noises? I know supra drivers get noises from their's.