[GMC Guy]

Originally Posted by donut

Good advise here. I'll throw in my few cents. I've burned up a couple NSS in the past few years. (Enough that I carry a spare in the glovebox now.) They are adjustable, just by loosening the 2 mounting screws and rotating the switch a little left or right. If your cab mounts are shot or loose, adjustment won't matter. Park and Neutral on the trans may be something else on the column.

Initial timing. A little to much can hammer the starter. On mine, it was fine cold, but warmed up it was slow cranking and sometimes would "backlash" (everything I read told me it was the heat from my headers also. Until it first "hammered") I'm currently running cheap Heddman longtubes, and my starter has been happy there for about a year and a half now. (knock on wood)

x2
cheap heddman longtubes, 12* of initial timing, no starter wrap, no header wrap, no problems :] hot or cold

i'd double check your timing again