The second variant, the TDK-7Y, doesn't exist at all until 3058.
The third variant, the Arrow IV-toting TDK-7KMA, doesn't exist at all until 3059.
The fourth and final variant, the TDK-7S, doesn't exist at all until 3065.
Barring an in-game time-skip, it seems unlikely that the Thunder Hawk would even be considered for quite some time.
Edited by Strum Wealh, 09 January 2013 - 06:39 PM.