SaviCatses,
Minor point but Hitec HS-425's are dual ball bearing, while Futaba 3004 are top ball bearing only.

ekrcflyer ,
Perfectly legal to use a full transmitter as a buddy box. If using Futaba transmitters with a Futaba trainer cord the "Buddy" doesn't transmit. Same holds true if you use Jr's to Jr's etc. If using Futaba to Hitec use the Hitec cable, otherwise the Hitec will transmit. If using Hitec to Futaba use the Futaba cable. 1st mentioned transmitter is the "Master" that actually transmits. In any case you can always pull the crystal on the "Buddy".
John