look at what I found in my bits and pieces...Motorcraft, but Made in Japan Motorcraft which is probably NGK or Denso or Hitachi outsource,
AG43CEU11...ND would be my top guess due to U-electrode feature which is old ND gimmick..got several of them maybe a set of 4, whatever they were originally intended for...
5/8 hex...check ..
but look at nose of it..although 19mm reach...last few threads have been machined blank (original) ..so no further concerns re fouled/jammed threads just in case that was ever a risk.
11 in part number indicates 1.1mm gap, which is slightly too wide, but soon adjusted down to correct 0.9mm
