The Carriage Assembly includes wheels, furks and axles. Comes in various track widths - which is measured from center of slide to center of slide across the boat.
The Classic furk was used in all SP's prior to Feb 2020, and works only with the Classic slides. The Standard furk is in all SP's since Feb 2020, it comes in a high and low version, and only works with the Standard slides.
You are in Canada, and we have a Canadian website here.