After looking through my servo stock, the arms that "Spartan Missile" has shown in his post look like the arms supplied with the old Hitec HS-700, HS-705MG and HS-800, HS-805MG ball bearing Mega servos. I still have a couple of 705's and 805's hanging around doin' nothing.
They have some pretty husky arms on them, and I like the ring to strengthen the spline boss.

Harley Condra
BVM REP
JetCat REP