Nope, that can't be it. 6.3 doesn't use naftpapp_connect.c, that's only a 6.0f_lsk thing.
I went back to the support site and downloaded all of the patches there, and compared the files in those zips to my 6.3 + the above patch file tree. One thing I notice is that the other patches on the site had an ftp library that was far older than the one on my HD. The one on my drive is dated 2/3/2006, the one from the support site is dated 8/16/2005. Not sure if that would be a problem or not. Adding a debug statement to the FTP process, I got this:
NAAppOffsetInFlash = 65536
Sounds wrong to me. And of course, now that module won't take an update via FTP anymore. I can't afford to keep killing modules to figure out what's going on here.
Anyone have any useful ideas?