Well originally we re-wired it to the back because I had a full stock on it, but I liked the colapseable stock better so I got the crane stock. The wires for the crane stock goes threw the middle of the buffer tube then connects to the battery in the stock. As for Raygis's question, in canadain the total was $77, the battery it's self was $52US.
http://www.onlybatterypacks.com/show...temID=11405.26