So I was parked on a hill yesterday, with the front of the car facing down the hill. Car was in park with ebrake engaged. I started the car, put my foot on the brake,put it in drive , released the hand brake then let off the foot brake to start rolling on down the hill. The car didn't move what so ever with no brake at all engaged. Then I tapped the gas and it clunked into gear and started driving perfectly fine. Then I put the car in to reverse in the same spot on the hill and it would clunk into reverse every time I would give it gas. Is this a transmission issue or a differential issue? The transmission is great and shifts amazing. The car only has 146000 miles on it and I can't imagine the transmission slipping and even if it was I wouldn't sit still while in drive facing downward on a hill. Maybe a diff issue? someone please help I've asked a couple mechanics but they didn't seem to help.

 

It could be several things associated with the driveline: U joints, central support bearing, etc. Since it started suddenly I wouldn't suspect the differential which is generally bullet proof. The car has to go on a lift and the driveline looked at. It shouldn't be very involved.