Most decent hobby shops should have Tamiya's Arrow family in stock or be able to get them.
Online, try www.squadron.com for kits, accessories and decals, not to mention reference material.
Here's what they currently have for Tamiya Do 335's:
http://squadron.com/SearchResults.asp?ScaleList=48&TypeList=1&ManuList=TM&Key=do+335
Fade to Black...