Where is the Neutral Safety Switch Gear Range Sensor located and how do I replace it?

This car has 42,000 miles on it. I just called the Ford Dealer where I got the sensor I put in, he looked up the PCM for this car and said that part is "long gone."

The dealer I contacted said the PCM for this car is no longer available. I can't understand that. Does that leave Lincon owners who need this part with nothing practical left to do but sell their cars for scrap metal? I emailed someone at the dealership who has been helpful in the past to verify if this is true, and if so, what they suggest to their customers that they should do. If you have any thoughts, insights, recommendations, etc. I would appreciate it.