The C-1's were pulled by Metra Engines leased from chicago before the arrival of the fl-9's. As far as I know, there is no reason why a 1500 could not pull a few bi-level cars in passenger service. We used to use them regularly with the old 2700's on the shorter trains, such as the oyster bay branch, or the scoots. The drawbacks would be no communication buzzer or PA to the engineer, so hand signs would have to be used. If a train crew had to stop the train, they would have to use the emergency brake. In addition, you would need more then 1 engine for traction, since the 1500's are getting old, and are not built for speed, and the bi-level coaches are heavy cars. In addition, you would need a 3rd engine, for hotel power. So with all the drawbacks, you would not see 1500's pulling bi-level coaches in passenger service. However if extreme circumstances arose, they could be used in a pinch.