Does anyone know the KNURL size for R33 GTS-T rear hubs ?

Im looking to upgrade from stock studs to extended studs on the Skyline R33 GTS-T !REAR! 5bolt spindles. I need to know the KNURL size before I can purchase the studs. Is it the 13mm or the 14.3mm KNURL ?

Thanks, if anyone knows exactly.

bump

knock one out of your hub and measure it?

not an option at this moment