Actually something I noticed in the CAD type pics seems to be a good giveaway as to what version RC4 you have...

http://www.rcmart.com/mylaps-transpo...l-p-35954.html

Looks like the new RC4 has 3 wires, but I'm kind of mystified as to why it would need a hookup to your RX signal, unless there is more planned that has yet to be mentioned.