I don't think they ever got to .018 unless it was an early editions...
indexing plugs??? uhhhh, hell yeah, usually takes me 20 to get 8 to line up right, so I buy 50 at a time to get maybe 3 sets..
crackle ??? yeah, it's got a tad of a pop to it
at 7400 it doesn't crackle, but dammmmmmmm does it sound good....there is no better music than an x pipe exhaust and a small block at 7400...