Ah, my cup runneth over! Now that I know the time period to look for, it gets much easier to spot examples under cars. Unfortunately I am modelling pre-WW2 - apparently I like to make life hard for myself - so the Symington trucks might be difficult to justify. Lots of Andrews trucks required for sure; I see a few on Ebay, but the postage involved in getting stuff to my corner of the world (and the prices being asked by the sellers, for that matter) means I'm probably better off making them myself - I have the means to, already done a fair bit of brass casting work....it is finding the time that is the hard part right now!
Many thanks to everyone for helping me out
Regards
Paul Woods
Whangarei, NZ.