I've just measured the one on my Goldstar and its 5mm over the threads. Hope that helps (you making one?).
I'd say mine feels a little loose and I'd like it tighter - you know sort of hangs at an angle instead of just straight down. That looseness also makes for a little play in it as you use it - I'd much rather it was firmer fitted.
Anyone got some ideas? I just can't get into using a trem arm that clicks and rattles.