I have a Duraspark on my race motor with the MSD 6AL. The vacuum has been removed and the plate locked down. Much cheaper than something else, its a rebuilt unit from O'Reilly's. I took the cast gear off and put on a bronze gear due to the solid roller cam (289). It's been in there since '94, had about 200 passes on it and finallybroke the roll pin. It now has a cut off nail with the ends swedged in its place (race track fix).