John C,
My K-line double stacks look to be smaller that the Lionel double stacks that I own. In fact the K-line double stack cars and containers look to be 40ft containers although they are marked 48 ft. Lionel's are also marked 48 ft. I keep telling myself to change the 8 to a 0 on the K-line double stacks. Nobody has ever pointed out the difference in size when running my inter-modal train at my clubs open houses so I keep running them. I try to keep the Lionel and MTH cars grouped together and the K-line cars grouped together so the difference in size is not so apparent. I do like both the Lionel and K-line cars as they are metal cars. MTH are nice too but not on par with the Lionel but they do weigh less and the metal cars do tend to get heavy when running a long train. Oh almost forgot at the end of my train I have a MTH car with a FRED which I really like.
JohnB