[427sharpe]

The belt number you list 15435--is a strayco number, which is an industry standard. The first 2 numbers designate width (in this case same as a 7 in Gates or a 15 in Goodyear and Dayco) and the last 3 are circumferential length--43.5 inches. So, an exact cross would be a Gates 7435, but the nearest they make may very well be a 7440 or 7445. Your number should cross directly to the other manufacturers. As an aside, the same applies to serpentine belts, like 1010K6, which means 101.0" overall length with 6 ribs. Just FYI. this numbering system is used by almost everybody in the US as far as parts houses go. Hence, a '7' belt is narrower than a 8 or 9, and a '15' belt is narrower than a 17.
As for the silver stuff on your plugs, it is anti seize compound to keep the plugs from galling the heads over time...a very good idea and also found very cheap in the parts houses. I make all my techs use dielectric grease on the top of the plugs too so that the wires dont seize on the plugs. Just dab some anti seize on the threads, and put a touch of dielectric grease in the spark plug boot when you install new plugs and you are ready to go.