Hunter,

I never used a pull-pull on mine because of the rudder arrangement. As I recall, the tailwheel that came with the kit has an extra long rod to it so it can be bent into the rudder, run through the fuse, and then out to the tailwheel. With the tail on that bird, it is impossible to use either the springs from a pull-pull set up, or one of the sullican ones that connects to a slider on the bottom of the rudder. I never got fancy with mine (just ran the long rod and it was fine), but I see three ways you could do it:

1) run two sets of pull-pull cables that exit at the different spots on the fuse to control both the rudder and tailwheel from the same servo

2) use the existing long rod that connects the two, but solder a control arm to the rod (or by an off the shelf version of a small nose gear arm that would use a collar and grub screw) and keep the controls internal to the fuse (you could do this with the elevators too) Just make sure you keep provisions for a bottom hatch plate so you can inspect it periodically

3) The overkill option, use a micro servo inverted and mounted to the fuse bottom to direct control the tailwheel with springs, and then run separate cables to the rudder.

On the Chipmunks I had (until #1 water landed, long story; and #2 suffered a battery failure) I went with the stock option with no problems. The large surface are of the rudder gives you tail authority pretty fast on the take-off runs. I built these years ago when my skills were not so good and didn't dabble into over-engineering stuff too often, like I do now. I have found that simple solutions often work, and can be sexy as well.

Good luck,