I have always enjoyed the K line Classic boxcars and scale diecast hoppers. Colorful and great all metal trucks, sound particularly cool on 90 degree cross track and 022's.
Happy I spotted this topic. I recently ran an all K line train behind PW Lionel 2339.
I own about a dozen k line classics, only seven would make the 031 return loops and figure eight on table #3. Here are a couple of photos.