Laid to the law:
Mine does it in any gear while accelerating, as long as I reach 2100 RPM before the shift. I tried duplicating it stationary, in neutral, revving to 2100. Nothing.
While cruising at 2100 RPM in top of gear, about 67 mph, it goes away when shifted into neutral and engine speed is maintained. Immediately comes back under load. I was thinking it of balance pulley or belt that reaches its harmonics at that sweet spot, causing the squeak.
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