I am no expert but to my knowledge the only phosphate process used on body fasteners is Manganese, not zinc phosphate. To the best of my knowledge body fasteners are generally manganese phosphate, zinc plated, cad plated or cad dichromate plated. A good reference is on survivor car photos posted in several threads if you do a search. Using the fastener spread sheet prepared by Jim in the library is and excellent reference (the best part is the sort function) as is the Master Parts Catalogue. I am fairly new at all this myself, but learning a lot by research. You can also use the AMK catalogs as well for reference. Are you doing a thoroughbred restoration, driver or trailered. FYI hot phosphating is parkerizing. I believe that there are a few other processes like insta black for example that does not require heating etc, but I have only ever used the phosphating process that requires a heated solution and submerging the parts. I find it gives the best result as well as the best protection imo, especially if you plan to drive the car. If you have a specific question about specific fasteners and can't find the answer by searching or researching, start a thread focusing on the specific fasteners as general questions about assorted fasteners are not specific enough given the myriad of potential finishes based on a multitude of variables.
