Have a look here at this great thread - it runs through all the different variants & versions of the RC10 up until the release of the new generation plastic chassis B2. It may give you an idea of which type of RC10 you want to watch out for.
http://www.rc10talk.com/viewtopic.php?f=35&t=13059
Have a look round the rest of the site there is sure some droolworthy machines on there
I have an original Gold Pan RC10 with the narrow front end & 6 gear gearbox - which I am intending to eventually re-build & clean up (even though it looks like it has very little use previously) with basic electrics installed for gentle running. I also have a 'Worlds Car' which was pretty much the last edition of the Ali tubbed RC10s with the Stealth transmission & hard anodised (machined) chassis & shocks - that gearbox is bullet proof (the basic design of which is still used for the B4). I restored the car & raced it with a 6.5 brushless motor in it! That car goes really well & in the few race meetings that I competed in, managed to keep a few of the modern cars honest
With these two cars I think I have the best of both RC10 worlds!
You best bet for finding your perfect RC10 is to search on ebay.us.... but i've noticed that prices seemed to have rocketed in recent months :-(