Taifun38

I am restoring a january 5th San Jose built 1966 convertible which in the past have had one front fender replaced with an original unit. Problem is I now have two different types of bolts fender to inner aprons(under the hood) and I am getting conflicting info on which ones are correct. I have seen numerous pictures of concours restored 1966 mustangs with these bolts cadmium(shiny zinc)and round conical washers but other sources(from people I really respect as well!)tell me I should have phosphate(black) with star washers. It may sound crazy to emphasize so much on this subject,I mean they both work don't they?But I really would like to have the factory correct look here. The rest of the car is pretty much all correct. Does anybody know? There may be a diference between early and late built -66'es