I have a reoccurring problem with my 08 4wd Suburban. The transmission/transfer case is whining when it get warmed up. this is a very high pitched whine- similar to electrical noise in a stereo system but is coming from the trans/transfer case. We now have 50k on the truck. we've had both the left and right front axle shafts and CV joints replaced due to issues with the front end. I've ben to the dealer with this issue three times and each time they say there is nothing wrong. I didn't have the issue until about 35K and it does not appear to affect the fuel economy. We're getting about 20 on the hwy. Has anyone else experienced this issue? Essentially my dealer has told me the trans will have to fail in order for them to fix it.