I need some help here. There are many reasonably priced sources for window assemblys for years up to 54 and from 55 forward, but only a few expensive sources with 54 window assemblys. So I was wondering if the doors from a 54 3100 half-ton were different from those of the 53 or 55? If not, why couldn't I save some dough and buy the 53 or 55 window assemblies and install them on my 54. Am I missing something?