Hood latch finish - phosphate?

[Gimmea250swb]

Oct 69 z/28.  What is the proper finish for the hood latch and guard that covers it?  The coloration looks different on this pic.  Are they the same color or is the guard just dipped very quickly?  To me, it looks like the latch is darker than the guard.

[169INDY]

Zinc Phosphate.
https://www.palmettoenterprisesparkerizing.com/

The resulting-colored results vary with, Metal composition of its constituent materials, Differing Heat treating of Parts, Duration in the solution, Prep methods, Surface profile,  Post treatment, Time in service, Exposure to Elements and Moisture, etc.

[70z28lt1]

Not to mention angle of the camera and lighting.  Look at the sides of the raised beads.  A bit darker to me.

[firstgenaddict]

The above photo is one I took of the Black RS/Z survivor AFTER I cleaned and coated the parts with cosmoline.
IIRC The entire part is plated as an assembly, minus the spring, which probably would be affected by the heat and the process.
Hood hinges and hood catches are typically Manganese Phosphate, which is darker than zinc phosphate and often has a crystaline look prior to oiling.
Palmetto also sells Manganese phosphate - I plated some hinges and catches a year or so ago.   

[169INDY]

Well the Photo of the Black RS/Z survivor is consistent with the New Car test HOT ROD magazine car,  in that the "Hook" certainly seems darker.
Cropped photo attached.


From Jerry's Book:
Hood hinges grey or black phosphate
Hood latch assembley grey or black phosphate

What does the New Judging Guideline book suggest?

[firstgenaddict]

Any plating difference could be the hardness of the metal being phosphated.
Here is another of the black car where the hook looks the same as the base.
And then of another survivor hood catch which I cleaned and treated with cosmolined too.

[bkhpah]

The original photo shows a serrated washer and a flat water holding on the horn's..BKH

[Gimmea250swb]

Thanks for the guidance.  Here’s the finished product.

[firstgenaddict]

The original photo shows a serrated washer and a flat water holding on the horn's..BKH

Is there a running change in the AIM for it?
Having recently gone through the legends judging guide, before dec 68 got the serrated zinc plated pinch point on the horn.
If not mistaken the crop is of the Hot Rod test car, early LA built with the 68 rear stripe arrangement.  09A or 09B.
Here is another 09B LA Z28 original owner original paint. with the serrated zinc plated 5/16 indented head pinch point also has the 68 Rear stripe layout.