The colors used to paint wheelsets & truck sideframes depends on whether they were the old oil (grease) or the newer roller bearing journals. The older ones always got coated w/ the oil/grease so they should be painted to give them a dirty greasy look. The newer ones should be painted a dirty rust color because they don't "leak" all over everything. A cheap way to get alot of rust paint is to take a sample to any place that makes custom paints like Home Depot or Lowes for a pint of it. Did that a few years ago & still have most of it left.