Walmart (unaffiliated) has the best deal on the Mercon V required tranny fluid for this transmission.

The correct filter for this R100 transmission (shallow pan) is the FT113: https://amzn.to/2Sv7xM6
....if you have a 4x4 that uses this tranny, or if you KNOW that your pan is a DEEP pan, then you need the FT114: https://amzn.to/3hkhu9P

...by the way, I ordered it and I checked, and from Rock Auto their (short pan) filter: "ATP TF173" is a direct fit and comes with a rubber gasket which appears identical to the OEM gasket on my E-350. I would be perfectly comfortable using the ATP filter and saving a few bucks, but since I ordered all 3 filters to make sure 1 of them fit, I chose to use the Motorcraft in my situation. That said, the filter I took off my vehicle appeared to have NO debris in it, and the debris picked up by the magnet in the bottom of the pan was all very small/sludge. In my humble opinion (as others, I've heard), it is not necessary to change the filter. Just try to replace all the fluid, and if you want to go the extra mile, clean the magnet in the pan (or you could purchase a few neodymium magnets and stick them on the bottom of the pan and just not remove the pan at all). :) Best of luck!