The PRR manufactured 83 locomotives between 1937 and 1946, ranging from powerful Q2 4-4-6-4s to incredibly fast T1 4-4-4-4s, none of which lasted even ten years in regular service. A footnote ...

The Pennsylvania Railroad had a reputation for blazing ... in Altoona against one of its M1a 4-8-2 Mountain-type locomotives. The M1a and T1 had the same weight on the driving wheels.