I extend the hardwood rails on each side of the fuse that hold the cross members for the servo mounts. take two pieces of lite ply. cut a slot on each side of each piece (perpendicular to rail) and run vlecro throught them. Wrap battery and recvr in foam, etc and secure with the velcro... Now I',m able to slide the components fore or aft on the rails.. or switch batt and reciever until correct balance is acheived.. then i screw into place through the "sled" into the hardwood rails, 4 screws (servo mounting type) per "sled".