I'm trying to find (but so far have failed) a modem.bin from an AT&T (i537) S4A running MF3. If someone out there has a rooted S4A running MF3, and if you have a couple of minutes to spare to extract a modem.bin, I'd really appreciate it...
Here's how to extract it. It can be done directly on the phone with a terminal emulater (e.g. Android Terminal Emulator or VX ConnectBot) or from an ADB shell if you already have one set up:
dd if=/dev/block/platform/msm_sdcc.1/by-name/mdm of=/sdcard/mf3-modem.bin bs=4096
Just be sure not to swap the "if" and "of"!