You said you heard the park prawl but I highly doubt that I suspect that engaged properly and as others suspected, the slip is a spline either at the front drive shaft (usually occurs at the transfer case) or one of the CV axles popped out (they are held only by a snap ring) either would make the sound you describe.

If either of the CV you should be able to see if it's not into the differential completely. The front axle spline is right below the driver's butt if left hand drive as in the USA. If either problem my understanding is you can defeat the front drive train by unplugging a fuse for the transfer case.

Neither the front axle nor CV is terribly difficult but use axle puller on driver (left) CV it's a bear to jimmy off with prybar etc very difficult.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)