..... patek 3417 came with dials along with the word : Antimagnetic. Some actually don't. Variations on the sub seconds, but one difference, is the actual printed sub seconds. 12-400 version came with a slightly larger circular sub seconds dial. where as 27-400 version has a smaller circular sub seconds printed on the dial.
Just like who Rolex 6263, where there is a version call : Big Eye. where by the sub chrono register is larger .