1993 Isuzu amigo s with 2.3 and 5 speed manual. Whining or whirring noise is most noticable in neutral, and can only be heard with clutch engaged (foot not on pedal). When I disengage the clutch the sound stops at the bite point. Transmission oil was changed 2 months ago, so not the issue. I think it is the input shaft bearing, but what do you all think?!