Thank you, that information helps a lot in looking at retirement dates of the T-12s. I am also now conjecturing that given the ruling grades between Alamosa and Durango with the exception of the Chama to Cumbres section, a T-12 could pull a four car passenger train w/o the need of a helper. Hence detailed information in the ETT regarding tonnage ratings of T-12s was not needed. Sort of automatic knowledge of when a helper was needed on the part of chief dispatcher based on the consist of the train planned for that particular day.