Small note/correction on the description, for the first consist you mentioned an SD40-2 on the Southern Pacific train, however Southern Pacific never owned SD40-2s, all of their SD40s were first generation, most of them were rebuilt and upgraded but they never received the designated of "SD40-2". The upgraded units, which were essentially home-build Dash-2 upgrades, were given the SP designation of "SD40R". SP did own two different models of SD40-2, but neither were conventional... The first of which were the Tunnel Motors, which were technically SD40-2s... The second was the purchase of 133 SD40M-2s in 1993, which were rebuilt from various older locomotives, mainly SD45s and SD40s, but again, these weren't "pure" SD40-2s, as they were all built completely new in second hand carbodies.
