I have a 2005 Escape with the 4 cylinder AWD and I'm not sure if I'm having a transmission problem or an issue with the axle or U joint. The vehicle makes a grinding noise when shifting from park to reverse and sounds even worse when shifted back to park. The car does not move under its own power but it can be pushed even when its in park.

 

Did it happen suddenly or gradually? How many miles on the Escape?

 

Maybe a little background might help here,
In the auto trans there is a parking pawl that a spring places into formed knotches in the output shaft piece when park position is selected. In vehicles without an AWD or transfer case the output shaft of the trans now prevents the differential from moving and also the wheels.
If for some internal reason there is a disconnect within the AWD or transfer case , the wheels are not held from moving. When the output shaft of the trans is not held stationary and you attempt to place the moving internal parts of the trans into park you get that ratcheting sound you are hearing and this can break the pawl in some cases . I would think there is a problem with the AWD system in your vehicle and unfortunately this can get expensive to repair. There are electrical as well as mechanical parts involved and try to have someone that is familiar with the system check it out.