Hi Jim,
So in terms of shock caps, losi also do aluminum bleeder ones, but they are about a tenner,
it looks like the rtr caps will fit the standard shock bodies as it would be abit stupid to make the rtr shocks different from the standard ones, (I may be wrong here)
in terms of springs, I didnt even realize that they did different sizes, it appears the rears are always 16mm though,
http://www.jemodels.com/electric-mod...tegory_id=1340
hopefully someone will be able to post up the front size, or provide an insight as to why different sizes exist!,
and don't worry about the ability to change the shock caps as this isn't what the springs rest on, its the shock preload adjuster that the spring sits on.