You WON'T be able to flash back to your previous radio if you don't have its img file/ZIP, and it's NOT provided here and a nandroid backup WON'T backup your radio. You can find some ZIP files for older radio here in joemm's thread.
For those who want the new radio but don't wanna install the RUU:
Suggested Method: Flash via PC using fastboot:(fastboot,ENG HBoot, PC required)
1. get fastboot/Android SDK on your PC
2. reboot your phone to bootloader -> fastboot
3."fastboot flash radio R:\radio.img"
For those don't have access to a PC, an update zip is provided(click here to read the original post and say thanks to joemm):
Here you go an update zip for the new radio:
android-info .txt file and radio 12.28h.60.140f_26.06.02.27_M .img file
MD5 Check Sum:
For those who dont know what this is, its the new radio zipped into an update file, to use it just place it on the root of your sd card, then boot into bootloader, select yes and it will flash the radio for you.
This must be flashed thru bootloader and not CWM recovery.
UPDATE: Heres a Mirror for the download thru Mediafire:
IMPORTANT: If you use the mediafire download you must rename the file from Vision_RADIO_12.28h.60.140f_26.06.02.27-PC10IMG.zip to PC10IMG.zip in order to use it. This is not needed if you use the dropbox link because its already named PC10IMG.
WARNING:Ignore this part if you don't know what these files are and how to use these files. Do backup your original files before applying these.
Reminder: the Wi-Fi module confirmed not able to work with most ROMs(including CM and previous stock ROM, so don't apply it unless you really wanna try and have backed up.
Don't forget to mount /system/ RW and set the correct permission.
Size: 410381 bytes
Will I lose Root/S-OFF/user data after flashed it?
This is NOT a full RUU, flashing this standalone radio image will NOT change anything to your root status/system/user data/etc. it's safe.
Make sure your phone is ROOTED and have the ENGINEERING HBOOT flashed on your phone. You can find a guide for doing this on xda-wiki. However if you're not familiar with such flashing thing, I will suggest Method 2(which doesn't require HBoot) for you, or don't flash it till you read and know more.