|Early F units usually came in set of 4, i.e., ABBA. The CB&Q found that for most trains on its mostly flat railroad ABA sets were sufficient so the ABBAs were broken into ABs with another newer A added. On the CB&Q an ABBA set was lettered ABCD and an ABA set was lettered ABC. In this picture we see CB&Q 165A, an F7A and 165B and C, F3Bs. The train is the early morning "Pick Up" at Milledgeville, IL (122 miles from Chicago on the Twin Cities Line). If the train had a number, it was never used on the dispatcher's line. Yes it is a heck of a train to be doing local switching, but it did weekdays.