A quick Google search didn't readily yield any relevant results. About how long in feet is a modern 31,000-gallon, crude-oil tank car prototype? I recently bought a bunch of Atlas' new TrinityRail 31K crude-oil tank cars in N-scale. The Atlas cars are pretty neat, complete with BLMA trucks (with blue hubs), 36" BLMA metal wheel-sets, and body-mounted, brown BLMA couplers (how are these different from the BLMA models?). Thanks!