I hope that you are just using the terms C, D, and K rations as a generic term for more current foods. To the best of my knowledge, D and K rats were a WWII item, and have not been produced (under that term anyway) since then, and C rat production was halted in the 1980's. I have a case or so of C rats around, but I don't believe I would want to eat any of them today. Original D and K's might even be collectors items...