Stan, yes there were HO scale models of these cars available...once. MODEL ENGINEERING WORKS (long out of business) had kits for them and they actually worked! You might look on the net or maybe at a train show for the old kits. I have one and it is a neat little model. Hope tyou can find some. Also, PRECISION SCALE made (or maybe still available) kits for them but may be a bit pricey. Contact them, a phone call will work or you may wait a long time to get an e mail answer.
____________________ It doesn't matter if you win or lose, its' how you rig the game.
for HO you might be able you get away with The Bachmann On30 ones IF you are working with a mineral/ore that is of a lower density like gypsum or similar. You need a big wagon to haul the maximum weight the track will stand as opposed to something like lead ore that is very heavy and a small wagon will get you very close the maximum axle loads a small mining line could handle without causing derailments with rail spreading or bending rails at joints etc
Moral of story: If you have the cars available, choose your industry to suit
Unanderra in oz