Heres a piece from a tech site, not sure how accurate but seems like what I remember. ..
The engines are great, but the PTU's (power transfer units) in it and the Edge are glass. On early models like 2010, ask for service records and see if the PTU has ever been replaced or serviced.
The fluid was initially rated as lifetime fluid, but there were alot of issues with seal leaks and pinion gears stripping within 25K miles. Later revisions in replacement units were better about it. Even if the PTU is rated lifetime, if you plan to tune and do any sort of aggressive driving, you should consider having it changed readily, and having a drain plug installed in the unit so it can be changed regularly.
2013+ models are allegedly a bit more robust, and have cooling monitors and fluid monitors installed so that the car diagnostics will tell you if the PTU needs to be services. In models before at least 2013, the PTU does not have a drain plug, and while many people have figured out ways to get the fluid out, the official method requires Ford to drop the PTU.
SHO's with the Performance Package, Ford Explorer, and the Police Interceptor versions of the SHO all have water jackets installed on the PTU and are connected to the lower portion of the Radiator for active cooling.
If the 2013 with the revised PTU (with a drain plug) is out of your budget, I'd stick to getting the Performance Package variant so you can get the actively cooled PTU.
