There's a very good chance that these locomotives were faster than the famous Mallard, but a record run was never held. They were certainly clocked above 120mph fairly regularly and their schedules required speeds of well over 100mph even when on time. It surprises me that US railroads lost interest in speed records; perhaps it was concern for liability?
YES! Definitely! Though I think if, a Milwaukee Road route, possibly Avery to Drexel would've had to be made first for TS, before locos for it get released.
