The GPS tailboom mount that comes with the system should fit most helicopters.  If not you would have to fabricate your own. 

Cut two strips of double sided foam tape and apply on either end underneath.

Install the tailboom mount making sure that it is leveled. 

Make sure the GPS is 20 cm away from servos, at least 10 cm away from the tail rotor and 30 cm away from electric motor and engines.

Use plastic tie wraps to secure the tailboom mount. 

Apply a 3M double sided tape on the tailboom mount.

Before placing the GPS down on the double sided tape notice the orientation arrow on the circle and a small arrow on the other side.  Use these references for lining up the GPS parallel with the tailboom.

The arrow should point forward.

For this review I decided to make my own tailboom mount.  If you decide to make your own tailboom mount make sure you use non-magnetic materials. 

I used stainless steel screws, carbon fiber and a Trex600 tailboom support bracket.

Cut a small piece of double sided tape and apply it underneath the GPS/Compass.

I cut the platform from scrap pieces of carbon fiber.

I used a string to line up the GPS/Compass.

As back up I used tie wraps in a X-cross pattern.