According to a "Chicago, Burlington & Quincy Railroad Co., Lines East of the Missouri River, Time Table of the Galesburg Division, of the Eastern District" employee timetable No. 44, Effective Sunday, September 25th, 1938, "Engines of the S-4-A (Aeolian) type when pulling light weight Zephyr equipment will use the speeds prescribed for such trains when powered by diesel motors". The "Aeolian type" was made up of the two streamlined S-4-A's (4000 and 4001), plus the never streamlined but upgraded similarly with all roller bearings and lightweight rods, numbers 4002, 4003 and 4004.
As always, Santiago, magnificent portraits of your "Aeolian type" !!
CBQ Bill - The Burlington Route herald, Aeolus medalion, pin striping and an anti-climber went on #4000 pretty soon after streamlining at West Burlington shops, as they were working out the most eye-pleasing arrangement.
