ORIGINAL: siclick33
JR 8411s used to be very widely used for the elevons. JR have since released new servos. JR 8321 are going in mine.
To synchronise them properly you will have to either, plug them all into different channels and mix them on your TX or buy a synchroniser such as JR Multibox or Futaba MSA-10 (one for each side). Either that or have amazing mechanical skills.
A lot of people use Y-leads and this seems to work OK. Some manufacturers kits (it has been made by several people) came with only one surface per side. I believe some people have permanently fixed the two together and used a single servo per side (if you're not bothered about the redundancy).
I was simply careful how I glued the horns into the elevons on mine and made sure that the linkages were the same, and I got the movement to be within less than 1/8" for the two halves of the elevon and the difference between the inside and outside one is the same on both sides. With this result I can not notice any roll-to-pitch, or pitch-to-roll coupling. With a little care, a Matchbox or MSA-10 is not necessary in a Kangaroo, and none of the guys I know with Kangaroos have used one.
I have (4) JR 8411's on my elevons...
Bob