I thought the center electrode was interesting
They were in there for about 13 or 14 years.
I replaced them with NGK G power.
Found number 2 spark plug wire had 2x the resistance of its equal length equal brand replacement, and the slightest movement of wire changed resistance. 5 of the other wires were within 0.5 K ohms of new Old read higher resistance, 2 were within 0.05K ohm and those were the shortest ones on cylinders 5 and 7.
As these 8mm Taylor hi energy series wires, were the first to last longer than 2 years, I replaced them with the same. Seems they bake faster than normal under the Van's tight fitting reflective engine cover.
It now idles so smooth again I have to check Dashboard to make sure it is still running.
Some of the grit/detritus accumulated after removal.
New Airtex/Wells distributor cap has brass center terminal and copper outer terminals.
I wonder how the copper will hold up compared to the brass.