When I use 2 channels, I mark the plugs by putting a short piece of heat shrink on one of the pairs. Many methods available to assure correct connections.

2slow2matter- Actually, he was talking about a single servo installation so there would be no Y-harness. After he he sets the differential he COULD use EPA to control total throw if he can't get it close enough with linkage positioning on the various arms. EPA or D/R would sacrifice resolution somewhat so the mechanical methods should be used first. IMHO