I was wondering if anyone could provide me what how many cars can a double-header of Southern 4501 and Norfolk and Western 611 (both from Peter's Trainz and are reskins of Ben Neal's locomotives) pull on the 'Norfolk and Western - Appalachian Coal' route included in Trainz 12. I couldn't find any videos on youtube of the two locomotives double-heading, so I'd like some help figuring out how many cars they can pull together. According to steamlocomotive.com, Southern 4501 originally had a tractive effort 51,638 pounds and Norfolk and Western 611 has a tractive effort of 77,899 pounds. This results in a combined tractive effort of 129,537 pounds. Given this information, can anyone help me?