A simple question,
i've these Wilkinson tremolo studs, as you can see on image there's a litte hole on side of the bottom of the stud.
So, is there a particular orientation for installing?
What's that holes for?
To run the bridge grounding wire to; it's easiest to strip a piece of wire bare; run the bare end through the hole and pull the wire through the route hole to the control cavity, then insert/seat the stud, pulling the wire taut as it seats fully. You only need to ground the stud closest to the control cavity; they just drill the hole in all studs so you don't have to worry about pairing them
Yes, you still want to line the hole up best you can with where the hole for the wire routing comes in from the control cavity; you can't get it exact, but the trick is to just have a little of the wire tightly anchored by the stud itself and the bare wire end pressed up against the stud body to make the grounding point.