I've been looking at various locos, specifically on ebay, which are listed as 'Big Haulers'. Frankly, the prices are all over the map and I'm not sure what one is buying. I saw one advertised with an R/C control that ran on 'C' batteries, listed as a 'BH'r'. So, is there something more definitive regarding the name, construction, quality? You guys said in another post the 'Anniversary' models had more detail. My real question goes to the mechanics, I can always add 'detail'.