You mean run the 2004 setup. Mine 04F7 std only has 2 wheels in back, both on the inside. You could prolly just get the setup from an Ebay part out 04 sled. I don't think the axle is shorter but the ends are attached differently to the rails (big nut on outside and you adjust track tension through windows in the track).
Why do you want to do this? It won't corner as well. Also not sure if the longer 136in track will like only having 2 wheels (vs. my 128inch).