i have tried the NS , BNSF , and a couple of more just to see if it was the engine type and the horse power at the 6000 . i wanted to make sure it was not me and i mixed them up , i did front facing rear and front facing. like i said before i work for NS and the more engines you couple up that gives you more power and on a daily bases, we can pull a consist over 10000 tons with one engine no problem .. and two engines can really pull with no problem . thanks for your fast responses . and if you need any numbers and stats to help you in any way i dont have a problem with that..