After reading through Marcus' excellent article, I have a theory about the nozzle finishes. It appears that Ford was progressively increasing the corrosion resistance, possibly in response to internal corrosion from washer fluid. 65 started out with zinc plate, which gives good protection, then for late 67 went to black, which I think might be S42 (see previous discussion, although in the photo it looks like in could be dark Mg phos.). In 69 the finish was zinc +yellow dichromate, which is another step up. Then in 70, the OD would be probably S43 (or maybe S43B) cadmium + OD chromate. And in 71 they gave up on steel altogether.