The early 4.0s had a FL-1A which changed to the FL-820S in about '00-'01 I think it was.
The FL-2005 is not obsolete just a fix to the Zetec motor for a really positive anti-drainback feature. The FL-400S was not up to the task so it would rattle on cold starts. Think of it as a SUPER FL-400S nothing more.
What is obsolete is the FL-200 which became the FL-300 used in some Tempos and what not which is a slightly short FL-1A but taller than say a PH-16 which is the FL-842.
The new filter was the FL-910 which is a small FL-820.
Also the new cartridge filter for the Hybrid Escape and 4 Cyl Fusion.
As we can all tell the filters are getting smaller for several reasons such a space and environmental.