look at the bottom of this web page for the exact spacer ring you need:
http://www.espritmodel.com/accesories_megagear.html
your setup is good, I used E-tech 1200 maH 3s1p li-poly packs.
they work great, here is a link:
http://www.parkflyermotors.com/secur...d=111&catid=19
let me know if you need any further assistance ... good luck, you will love the 3DX!