Trying to diagnose a new noise before I crack the diff cover (again), pull the axles, or decide if it's worth taking the car to the dealer (extended B2B warranty). I started to get an periodic/oscillating whir (~1Hz) when accelerating out of corners at high lat G and high load, especially in 3rd gear. I was in the canyons and was worried about the bearings or the diff failing so I took it easy after I started hearing the noise and did not hear it again on the drive home. Clearly sounded like it was coming from the rear and only happened under the above conditions. No leaking from the diff, axle play is negligible, no rumbling while turning, no loose driveshaft bolts, no grinding or other noises while spinning the rear wheels off the ground, and no change in diff/gear whine during normal driving. I do have a lot of backlash at parking lot speeds that seems to be slowly getting worse over time, and a high speed vibration that I have not been able to track down. Mostly stock Boss at 43,000 miles and 15 track days, street tires only (stickiest being NT01s), recently installed Koni Yellows, Steeda Boss Springs, Boss 302R/S trailing arms and relo brackets. When I changed the diff fluid a few track days ago the fluid was in surprisingly good shape and the diff visually looked fine as far as I could tell, but I have very little experience examining diffs and I didn't get the panhard bar off so I couldn't look too closely (don't worry I filled it back up using the correct hole). Based on when the sound occurs I'm leaning towards diff or diff bearing issue, but any other ideas or feedback would be greatly appreciated! Thanks!