Hi Fred,
sorry for the delay, we spend few days on the MakerFaire2016 and in few hours I´m away vor vacation, 2 weeks! 😉
You can use all Walkera Motors for Gimbal G-2D and G-3D all are named something like G-2D-Z-03, WK-WS-22-001 and more. All this motors are same for our using, just the axis are in diverent lengths or the color is black or platin, but it doesn´t matter in any case we have to cut the axis.
Sometimes I orderd it from BangGood and from GoodLuckBuy or Ebay shops, here are one option:
http://www.goodluckbuy.com/walkera-brushless-gimbal-g-2d-part-g-2d-z-09-brushless-motor-wk-ws-22-001.html
You ca also order it from Walkera China direct, few month ago I ordered there 10 pc too!
all the best!