IL National Guard
For handheld radios, try the 148.0 - 150.770 MHz band first, followed by 138.000 - 144.000 MHz (all NFM). A few IL National Guard facilities in the northern portion of the state have been noted in the past on 150.6875. NG vehicles and helos use VHF low band (30-88 MHz) as well.
Please let the rest of us know if you can confirm any of their freqs, as reports of IL NG radio traffic have been "few and far between" in recent years.