hi,upnorth is right in saying about the raf .
normally there is a stencilled unit id("conn 021",short for conningsby,pylon number 021)
there is also warning triangles where eru's are fitted)electoexplosive release unit).on the tornado gr4 there are also locking indicator marjings to show the position of the weapon locks.
i'm not sure if ww2 planes had markingg on the pylons.as a armourer.i know about the modern stuff,but not to sure about pre 1960.
try the raf museum hendon or try www.rafarmourers.co.uk
merv