455.750 will be for ground vehicles, not for aircraft.
so i must be hearing things then, the other day i heard:
eastflight 940x – pushback clearence and t/o 25 clearence
starburst one (metro radio traffic helicopter)
Speedbird 13k – t/o 25 clearence (also said the new clearence frequency is a great help)
Air France 1173 – pushback clearence and t/o 25 clearence
easy 6475- pushback clearence and t/o 25 clearence
jersey 3471
Speedbird 12N
eastflight 4096