i was backing my 02 yukon up the drive way and heard pop/clunk and a high whine. I figured I trashed the tranny. So I put it in drive (hopeing I stiil have drive) drove down the drive way and up a little hill hit reverse and backed up. It seemed like I had reverse but I was on a hill too, and drove back up the drive way. It whined the whole time and even a little louder in park. Please tell me What happened?