Be sure to check the ball tongue height that you need for your trailer to ride level. The standard install on an E70 leaves the ball much lower than it is on an E53 X5 std. install. So low, that I had to flip the ball over to the other side of the tongue for my trailer.

BTW if the ball is stalled correctly (lost of torque) you would need a serious breaker bar or a long cheater to flip the ball.

Funf Dreisig