3C3Z-9E527-AA (Original C91 injector) was replaced in 2003 with part number 3C3Z-9E527-ABRM (C94) and then later with 3C3Z-9E527-AE (C95). These part numbers were for engines built before 9/22/03. The latest injector number is 4C3Z-9E527-AA (C2 or C92) for engines built after 9/22/03
. The difference between original C94 & new C95 was internal change to clevis. Had to do with plunger suffering from side loading which then causes raw fuel to flood and enter the engine oil crankcase. Design improvements aimed at preventing scuffing.
Also (from Ford):
Change in 2004 from the 2003 design:
DLC (Diamond Like Carbon) Coated Plunger
• The injector plunger has had a DLC coating applied to it
• The coating will further increase the robustness of the injector against poor fuel quality/water intrusion and will reduce the risk of internal scuffing.
Note: This injector has different operating characteristics and can not be interchanged with non DLC injectors. Installing the incorrect injector could cause erratic or rough engine operation.
They will certainly fit. Your call on whether to use them or not.
page 27 (or 29 - can't recall which) of the presentation in the link above.
As I read it, 04 model injectors (after Jan 04) should be the updated version and be fine for all later models. 03 (and very early model 04 injectors) are not recommended to be mixed
with the later versions.