Joey,
Wish I could help in this area but I can't. I have never seen them used in Futaba. I have one 500mah and I believe my other is a 600mah. The plugs are right there in the compartment so swapping is easy. The 600 mah NiMh is new because mine a Nicad. I'd like to get a bigger capacity batt for the transmitter as well but I think I'll use NiMh batts.

Ask Bax over here~ http://www.rcuniverse.com/forum/forumid_125/tt.htm

He's the moderator and guru for the Futaba radios.

Let us know what he says.

Blessings,

Jay