In the late 60's & early 70's train #5 was the last primary mail train on former NYC New York/Boston to Chicago. What was its' eastbound counterpart???
This might be a better question on the PC forum as that train was first listed in PC ETT No. 1 of April 28, 1968.
It appears to have replaced NYC RR No. 3. PC played with the numbering and maybe somebody on that forum
has done the research. Jack