Just received coil packs and plugs that have gotten rave reviews on ebay. I specified that I have a 2003 5.4L L-code and got AGSF34FMF4 plugs. Owner's Manual and Motorcraft website say AGSF22(WM) with no mention of this plug.

I've searched and see that is important to use the same plugs but have no idea which part numbers may have superceded others. I also searched for more info on the AGSF34FMF4 and came up blank...

I asked the seller the same question... Should I return these?

 

Some plug designations have been superceded by FORD.
You need to go the a dealer parts department and ask, to see what the latest spec is. The EBAY people won't know this info.
Sometimes the new plug causes problems.
I found this out and it caused a long search and 3 sets of plugs to find why my new plugs only lasted a short time, then another new set only lasted 500 miles before random missing began again.
A search began to uncover information that has now resulted in a fix to my problem.
I am not saying you will have any problem but how to get the info you need on plugs and what could happen.
Good luck.