lutherkb wrote:What exactly does the CTE mean? And how does one spot these differences?CTE stands for Control Tractive Effort. It is software that reduces the tractive effort of the locomotive when used as a DPU in manifest service. There is no visual difference in the locomotive, its just the computer software and all UP AC4400CW's are being upgraded with this software during overhauls. UP is the only railroad that currently uses CTE.