If you can hear it in 5th & 6th at the same speed, it seems to rule out the tranny and point to the belt? Am I missing something? I hear the noise on my bike too. I am quite sure it is the belt. I'm pretty sure I can fix it with a louder exhaust....
2011 XR Midnight Cherry, Hard Bags, Vic htd grips & seat, Vic medium Windshield, unlocked speedo, Lloydz Air filter, VFC III, Lloydz ATS +4, Vance & Hines slip ons
1993 Vulcan 1500 (sold)
1981 Yamaha Seca 750 (ridden into oblivion)
1977 Honda 550 (sold)