[buzzinhalfdozen]

From my experience once a gear set has been run "loose", it's all down hill from there. The gear may last a while hard to say however the damage is done. When the pinion bearings no longer hold the pinion in it's proper position the gear mesh is thrown off hence the whine, tightening the nut and bringing it back only to have a worse whine indicates that the teeth on the gears have been damaged. you have 2 choices....keep running it to see how long it lasts, or change it now. The downside to the first option is you will risk damaging more parts if the gear set jams while on a run, cars don't handle well with the rear tires locked, plus potential other drive train victims. My suggestion.... replace it now and save yourself head aches down the road. Joe