4mm ball studs with 3mm"ish" shank

[TRX-1-3]

I've ordered some Tamiya 4mm ball cups.

I plan on reaming the sleeves to accept 4-40 threads. But I still need to source some ball studs that have a 3mm threaded portion. I think a 4-40 threaded portion would also work. It's not a runner and I just need the look, ya know? I know a 4mm ball is a little under spec'd for a racing buggy but if I can pull this off it will look bitchin'!

Thank you for your time/help

[juicedcoupe]

Just for reference, Tamiya "4mm" ball studs actually measure about 3.8mm. All the ones that I have, have a M2 thread.

[juicedcoupe]

The ones on my Losi Mini JRX2 measured 3.9mm. The thread looked like M2.5 (maybe 2.6). If used with a helicoil, they'd probably work.