What are the differences with the driving wheels and driving rods of Bachmann's original HO scale K4 side rods and driving wheels #5404 vs the net edition #1351? Are they the same and interchangeable? I've been contacted by an owner of a #1351 wheel/rods set - if they are interchangeable, my problem is solved. I recall the #5404 engine had gearing problems creating the need for a redesign.