Any idea of the length of train and gradient that the 66 can haul? My Farish 66s do fine with 28 4-wheel wagons on 1:40ish but struggle with 12 of the new Freightliner hoppers, which seem much heavier and have more rolling resistance. The Farish chassis casting fills most of the body, but I think I'm right in saying the Dapol has more air inside and therefore possibly scope to add lead.