Good Article on the PTU! Z
Power Takeoff Units -new bearing designThe power takeoff unit (PTU) has been a service concern on some PI Utilities. There may be an excessive oil smell when driving, the AWD may not work properly, or the PTU housing may be cracked, leaking or noisy. The cause of the PTU damage is the excessive torque loading of the idler gear, which causes the bearing to walk (move) into the housing.
In January 2014, a Full Face Thrust Washer, FFTW, was introduced. This new washer was designed to prevent the idler bearing from walking into the aluminum case. In October 2015, a second change was made, in this case a loose-fit idler bearing. In dynamometer tests, this bearing design change showed a twice life improvement over the FFTW design.
In June 2016, a third change was made. In this case, a new bearing design, one without drawn cups, was installed. This eliminated the walk mode of damage. Dyno testing shows a three to four times improvement over the FFTW design. For both the PI Utility and PI Sedan, the PTU is covered under the limited powertrain warranty. All Ford Police Interceptors come standard with a five-year/100,000-mile Extended Service Plan for the powertrain.
http://www.hendonpub.com/resources/article_archive/results/details?id=5858 . Z