I was driving down the high way at 75 with cruise control on and my car violently down shirted and then sped back up. It did it agian. then the third time the rear wheels locked up and I went into a skid. I kept it under control and no one was hurt. But here is the tecniacal part. We checked the differental and its not that. we checked the gear box and its not that. We cant spin the drive shaft what so ever. So I have a tranny guy coming to look at it at 5:30 and he will check it out. Could it be the transfer case. I hear that my car was recalled becasue the transfer case seal is bad. So that might be all dried up and caused the rear wheels to lock. Any imput is appreciated.