Set K5358W is pictured on p70 of Greenberg's Guide to American Flyer S Gauge, Volume III Sets. At least in the set pictured the 4 straight tracks were not in a 700 yellow box, they were packed loose. If you do not have access to that book I could post a copy of p70.
I don't have that book.
I have the first edition of the Greenberg Price guide and the David Doyle book.
I did not see anything about large and small motors, different flange sizes, or direct versus plug board wiring in the books I have. All stuff I learned here.