He must have been. I did the same in 1964, standing in the rear vestibule from Lafayette into Dearborn. It was February and very cold, but worth every freezing minute! Here's a photo I took toward the end, when we were cruising up the C&WI into Chicago. See the "Tim Swan" photo CD for more, available from the MRHTS Stores Department.
And for Walter, see Question 590 in the new August THL when you get it for a couple of good answers. Short of somebody discovering MONON Corporate B.O.D. minutes or something addressing how the diesel colors were adopted, we will probably never know for sure.