I found this in the Sullivan page
http://sullivanproducts.com/ContSysAccMainFrame.htm
Double Ball Joints
Elevator Splitter. Two ball links with locking sleeves connected to a plated steel “dumbbell” allows motion from the servo arm to two parallel surfaces at the same time.
S558 2-56 Threaded "Dumbbell" and sockets
S559 4-40 Threaded "Dumbbell" and sockets
Any other option.