Thank you for asking, your question has prompted us to put that information in our price list soon.
In fact, both airframes are exactly the same. The TUNDRA kit comes with both attachments in the double floor to accommodate either conventional or tricycle main gears. You could actually switch from one configuration to the other after building the airplane.
The only difference is that the tricycle version comes with the engine mount, since the nose gear attaches to the engine mount. That explains why the tricycle option is a little bit more expensive.