About 1973 the Milwaukee ran the first all container train from the Port of Tacoma(tideflats Yd)to Chicago. The train was on the 7AM hot sheet as a TEST train departing Tacoma on Sunday and arriving Chicago on Tuesday. I was called out of Portage,WI. for an extra east test train in the east pool for the train as Engineer to run it to Milwaukee. We had the Traveling Engineer with us but I don't remember any business cars...maybe they were on the rear. Usually the Milwaukee would run the X5000 Dyno car with something like this but I don't remember it. We were told by message to operate train at 60mph conversent with the rules and special instructions.The train was all single stacks but I don't remember how long we were...we still had a caboose at this time. All went well and we changed crews in Milwaukee in about 90 minutes from Portage. I don't recall what the end result of the test train was or whether we had any more.