Thanks for the suggestion Bob.
I am looking for input/confirmation on what the factory finishes are on the following fasteners:
1. Intercooler bracket to intercooler - 4 fasteners - phosphate?
2. Throttle body to intake - 4 fasteners - gold cad or yellow zinc?
3. EGR to back of upper intake - 2 fasteners - zinc?
4. Upper intake to lower intake - 4 fasteners & Blue Green nut - zinc?
5. Fuel Rail - 2 fasteners - phosphate?
6. Throttle cable plate - - 2 fasteners - phosphate?
Great to see someone else interested in the finer details of these cars.
The best way to determine the original finish is to look at the backside of the bolt/screw head. Typically this surface has been protected from the elements and still retains the original finish.
From my experience and pics of low mileage cars...
1. Intercooler bracket mounting bolts should be a dark phosphate like manganese.
2. Throttle body to intake mounting bolts on a later '86 are zinc dichromate. On a '85.5 they are actually gray phosphate, so there is a changeover somewhere in between. I need to look through some more pics for an early '86.
3. EGR mounting - I will look through my pics
4. Upper to lower intake are manganese phosphate (dark). The nut securing the arm to the p/s - alt. bracket is baby blue.
5. Fuel Rail - I will look through my pics
6. I need to look at the throttle cable bracket mounting bolts again. Some pics appear to be phosphate, but that could be the lighting.
Hope this helps... or at least generates more discussion.