RE: Need some info on a HD DuBro Pull Pull set up
Arm on the servo has to be the same width as the total width of the rudder horns attach points - if rudder horn is wider itself, screw the attachement points inwards - do not glue or loctite them.
Similar, if servo horn is wider (e.g., 4" instead of 3"), attach to inner holes.
There are different theories regarding the cables crossing or not. My belief is that if using kevlar (no interference), then you can cross if it gives a better direct line (no binding) between servo and rudder attach point. For crossing wires, I use the offset arms (see picture below).
I've seen competitors do this on very large planes, so I assume they know what they are doing...
I attach below what the linkage looks like on a 30% Lanier Extra 330 using a 4" SWB straight arm, DuBro ball links, Airwild pull-pull fittings and the DuBro rudder horn. I also have a picture with the offset SWB arm.