Why on Earth did they say you needed all of that work? It looks like they are trying to take advantage of the ignorant people. I'm not implying that you are
I'm talking about the people that take their vehicle in for what should be a simple fix and leave several hundred dollars poorer. Let's see on your list:
1) Change differential fluids - In your Ford manual it say's that the differentials are filled for life. The only time you are required to replace the fluid is if they get submerged in water, frequen towing or if they are appart for some other repair. Besides it should only take a couple of hours to do both. Add a few quarts of fluid and the price still comes out way less than $525.
2) Transfer case - Due every 30K in the severe duty section. Did it myself in about 20 minutes. Total cost was 2 quarts of Mercon ATF.
3) Emission cleaning - Probably their throttle body service. If you haven't failed an emission test and aren't having any problems that would indicate that your throttle body is full of carbon, it is just wasted service.
4) Injector service - Again isn't listed as routine maintenance. Most if not all gasolines shouldn't foul up you injectors. Even the two guys that come on TV on Saturday mornings recommend that you avoid this service unless you are certain that you have a clogged injector.
5) Change air/fuel/PCV - An air filter costs like what $8?, my 97's last fuel filter cost me $10 at Checker Auto Parts. I replaced it in less than 30 minutes and it was the first time I attempted to do it. Even taking it to a garage and paying someone should be less than $50 P&L. PCV, tell your dealer that you would like them to replace it for free since it is in your warranty booklet that Ford will replace it at no charge at 60K miles. I did, and the Service Advisor said that I was the first person that pointed that out to him.