First 2X4 prototype in 1999. Note carbon front disc and drilled out snowcat front rim and Sun/Ringle rear. This bike also had the smaller 1.75" top and down tubes.
This was a later prototype in about 2002. Two of these were built. Pictures are on the bikes page.
Drawing showing the zone in which the rear wheel can move (area in black at left). This made for a very active rear end that glided very well. The shocks could be individually tuned to adjust ride characteristics.