If you want to go the inline tranny filter route then take a good look at the Magnefine product. They claim sub-micron filtration and have been adopted by a rather impressive number of OEM and Fleet operations. It's also detailed as part of a transmission TSB affecting a number of Ford vehicles in response to ATF contamination: Ford TSM 00-23-10
The most impressive thing about this product is the bypass feature which protects your transmission in the event the filter media becomes overloaded:
Best of all, a current Internet special price of only $19.00!![]()