You can use a FL1A size filter if the engine installation allows. You can use virtually anything with a 3/4-16 thread. I think you spec' a FL400S size can ..but the gasket is "functionally" identical to all the normal Ford filters.
Your spec'd filter in wix
51516
UPC Number: 765809515161
Principal Application: Ford/Merc. Cars + Trucks (81-05), Chrysler/Jeep (02-05), Mazda Trucks (94-05)
All Applications
Style: Spin-On Lube Filter
Service: Lube
Type: Full Flow
Media: Paper
Height: 4.828
Outer Diameter Top: 2.921
Outer Diameter Bottom: Closed
Thread Size: 3/4-16
By-Pass Valve Setting-PSI: 8-11
Anti-Drain Back Valve: Yes
Gasket Diameters
Number O.D. I.D. Thk.
Attached 2.734 2.430 0.226
FLIA size in wix
Part Number: 51515
UPC Number: 765809515154
Principal Application: Chrysler Family of Cars/Trucks (57-70), Ford Family of Cars/Trucks (57-00), Mazda Trucks (94-00), Toyota Landcruiser (71-96) - (Two Quart version is 51773)
All Applications
Style: Spin-On Lube Filter
Service: Lube
Type: Full Flow
Media: Paper
Height: 5.178
Outer Diameter: 3.660
Thread Size: 3/4-16
By-Pass Valve Setting-PSI: 8-11
Anti-Drain Back Valve: Yes
Gasket Diameters
Number O.D. I.D. Thk.
Attached 2.834 2.462 0.200
I use this on my daughter's Taurus that also spec's the 400S filter.
I'm pretty sure that you can use just about any Ford filter except those for the new(er) modular engines ..which use the metric thread ..so take your pick
The standard PermaCool relocation kit will spin right up to your filter land. It includes all the threaded inserts needed and the basic size of the adapter (since most filters fall into a similar size) is just right for your Ford/Mopar filter mount. They include an adapter for other, larger, filter mounts that you won't need.