well in my case I married 3 WK axles(had to modify one to have an input, and output shaft) to a SCX10 Tranny, and frame rails, and used brass tubing to extent it a bit to slap on the rear axle.
But that was just what I had laying around from a past project if I had to do it over I probably would have used a SCX10, or even maybe the new SCX10's(its narrower) axles to keep it simpler.