BigDogRacing
The thrust race is pre-built - It has two grooved plates and the balls are in a brass cage.
You can't thin the cone down any further because the thrust race will touch the main axle ( It sits over the threaded part when assembled ) Using a 3.1 axle or an IRS axle there is about 1/8" of thread showing past the thin nyloc nut when assembled.
Never had one come loose on any axle yet and I have converted over 20 axles for friends.