Richard,

Will add a little to your questions.
Photo #3: CRI&P 425 (EMD BL2) is leaving La Salle St. station in Chicago, IL.
Photo #4: CRI&P 401 (F-M H15-44) also leaving LaSalle St. station, Chicago, IL.
Photo #5: Wabash 495 (EMD GP9) is at Dearborn St. station in Chicago, IL.
Photo #6: Monon 25 (Alco RS2) is leaving Dearbon St. station in Chicago, IL.

The time period of the four photos is probably 1964 - 1966. The Rock Island units would come to Peoria, IL. on the weekends powering freight trains out of Blue Island, IL. Took a 35mm color slide of the 425 and 401 together at the Peoria, IL. engine facility on Saturday October 10, 1964. 35mm color slide of Monon 25 in Bloomington, IN. on Saturday April 9, 1966. It was renumbered to 55 later, not sure when. Never photographed Wabash 495 or N&W 3495. N&W absorbed the Wabash on October 16, 1964. 35mm color slide of Wabash 493, in the paint scheme of the 495, on commuter train #113, on Monday July 5, 1965, in the same location as photo #6. By the end of 1966 most Wabash units had been renumbered ant painted for the N&W.

Do not recall seeing these photos.

Hope this helps.

Ed Johnson
Peoria, IL.