Hi Guys - A couple of 3+ years ago, I built my first kit which was a 4 * 60 and posted a building thread here on RCU also. During that same time period, one of the other guys was also building a 4*, and he added retracts to it. He posted pics here on RCU, but I don't know if you could still find them or not. Looked and sounded like it worked pretty cool. I do remember he went with a mechanical set with retract servo. Have fun with your builds