Hi guys, i wanna get a gearknob custom splined, what are the measurements i need?

Hi mate.
Accross the top of the gear stock is 1.5 cm.
The gear knob hole is 1 3/4cm accross.
I know this because my gear knob came of the other day
and i haven't got around to sticking it down again
Hope this is of some help.
Cheers Mark.