DO NOT mix ICS and GB Radios. DO NOT ask how to install these radios, I feel if you must ask how your not ready to handle the task and the demons that may occur, there are many threads on how to do these things.
If you end up goofing up and realize you have no or fluctuating 4G do the following.
1. Flash the RUU of your choice.
2.Upon installation flash nothing! reboot into HBOOT and select clear storage and let it run its course (remove sdcard if you want even though it wont wipe external card
3. Reboot phone normally verify everything is smooth
4. Optional- Flash Eng Hboot for GB or the Juopunutbear modified Hboot for ICS
5. Alternate Fix- Ive heard that you can flash stock recovery to the phone via fastboot reboot into hboot and select clear storage and will have same effect to get 4G working. Custom recoveries do not work to fix the issue via wipe menu. I only state use RUU of your choice as it gives you a clean slate and can be ruled out down the line in troubleshooting
Heres my compilation of CDMA+LTE Radios.
They are available as they came from RUU or Individual for mix n match.
From the 1.02.605.6 RUU (0.95.00.1017_2r and 0.95.00.1013r)
Here is the 2.01.605.11 RUU radios (these are the latest Official OTA radios for GB as of this posting but they work well for me on ICS....0.95.00.1118r and 0.95.001223r)
Here is the Leaked CDMA and LTE radios from Ics 3.11.605.22 (1.22.10.0310r and 188.8.131.528r)
Cdma .1017_2r cdmagb1.zip
LTE .1013r LTEgb1.zip
Cdma .1118r cdmagb.zip
LTE .1223r LTEgb.zip
Cdma .310r icscdma.zip
LTE .308r icsLTE.zip
Theres so many people who ran into this issue and too many to name who risked there device in hopes of a fix, so a BIG THANKS to all who posted and suggested/tested various ideas in the 3 main threads focused on getting 4G stable