I didn't need to grind anything on the case, however I needed to grind down the studs for the power wire hookups to the starter so they wouldn't hit the side of my 440's block. Cut them down a bit, had to cut down the big one quite a bit, then clean up the threads a little. The nut still gets full thread engagement but not any extra stud sticking out anymore. Works great and no problems. At one time I thought the starter was junk, but turned out to be a slowly discharging battery due to a faulty voltage regulator.