Exactly. The Mustang ones actually include a programming box so you can test them, setup sequencing doors, tail wheel etc.
The box that comes with the Spitfire retracts has an input for a separate pack, that if its hooked up draws power from that instead of the rx pack.
Everything including the machined and working oleo struts, and control box is included, you install the retracts and plug in a lead to your RX and you're done.