The 68B is an old heli from 2006 or so and it came with the 701 FM TX. Where have you seen it as 2.4GHz?

There is a 60B which is a pretty new heli and it comes either with a 2801 RX with a 2801 TX or a 2701 RX with a 2601 TX. But a 4 channel 2401 TX can not be used for a collective pitch heli as Tedstrickland desribed.

/Hans.