This sign has been by the Manhattan-bound platform at the Woodside Long Island Rail Road station since I started using it in 1992, and probably long before that. These days the closest Alcol Realty is in Ornageburg, NY in Rockland County.
IL stands for ILlinois.
Maybe they drank themselves out of business.
This sign must date to the pre-multiple area code days. IL 8 -6600 would have been 458-6600, with I=4 and L=5 on the phone keypad.