I have a 5xxx VIN series 1 that I am trying to bring back to life. All NOS door strikes I have seen on ebay et al are bright white.  I am absolutely certain mine were yellow zinc along with the bolts that fastened them to the car. 

Has anyone else seen that on an early car?

All the original Z's I've seen have zinc plated (silver) door strikers and latch mechanisms, including the bolts. 

The early Z's have zinc plated (silver) door strikers and latch mechanisms, including the bolts. 

If you are not the original owner of the car it's possible a previous owner had them replated in the incorrect color of yellow zinc.  As the others have said above, the correct finish is clear/white zinc.