As far as I know there are no rear sensors that control AB's. They are only for front end crashes. Usually, as I understand it, they go off when the vehicle's front end crumples to a speciffic spot, or receives a perdetermined inpact force sufficient enough to cause movement in the sensor. If you didn't receive enough damage to cause the front end to crumple then the later condition is what caused the sensors to go off. What I don't know is wether or not they reset, as there is an internal part to them that actually moves causing contact, setting off the AB's. With that answer unknown I would be concerned that leaving those in place, could cause the new AB's to go off as soon as power was restored to the circuits.
Just to make things clear, very simply put, this system consists of AB's, AB monitor, and crash sensors. The AB's are plug n play, the monitor just does checks to see everything is ready electronically, and the crash sensors actually trigger the event. (doing something stupid can also trigger the event. ALWAYS USE CAUTION CONCERNING AB's)LOL, disclaimer required for some people.
I suggest you contact Todras, via PM, and order a Ford CD for your year of Tour. It is very reasonable, about $5 (I think), and has everything you need to know about your situation on it. Electrical and mechanical information with lots of pics and proceedures.
my 2 cents,
AF