"As far as the tx/rx combo they are only for the Japan market."

FYI clarification, not true:

The kit itself is called a Japanese Market kit, but the Tamiya JS-2 Japan market kit 2.4 radio (in a black case and branded Tamiya) with a left stick self centering spring installed, is the same radio as the silver case Futaba 2.4 sold in the USA and the USA radio does not have the self centering left stick installed.

That is the radio transmitter difference. Get the Futaba 2.4 left stick self center parts here in the USA:

Hobby Services
1 217 398 0007

Parts Needed:
1. HSP78901 1M10A18201 ST-53 Swing Arm
2. HSP67450 8M00F01002 ST-41 Spring

Also, the kit includes a battery charger that does not work in the USA unless you have a voltage converter and that is the only item NOT for USA use found in the kit.

I know, I built a first JS-2 kit from the AAF Museum and a year later bought a Japan Market JS-2 Kit from Banzai Hobbies.

Enjoy your JS-2 build, fun kit.

John