Union Pacific SD45Ms #60-65 were rebuilt from standard EMD SD45s by Morrison Knudsen at Boise, Idaho, during 1980 to 1982 as a test program using Sulzer 16ASV25R-30 diesel engines from Switzerland. The rebuild effort required extensive modification of the car body to accommodate the new engine. The most visible changes were an additional two inches of car body width along the hood sides, and a screen intake at the rear of the car body on the left (fireman's) side. All six units would be retired by the UP in Dec. 1983.
