[1][2] The locomotive was jointly designed by Progress Rail and Norfolk Southern Railway.

[3] Three locomotives were built; they were manufactured at Progress Rail's Mayfield, Kentucky factory.

[3] The locomotives operated by Norfolk Southern worked on freight trains in central Illinois, leading to speculation that they were being tested, as Caterpillar's headquarters are located in Peoria, Illinois.

[1] The process of converting an SD50 to a PR43C altered the external appearance of the locomotive; the original radiator section was replaced with a larger one similar in appearance to that of an EMD SD70ACe or SD70M-2.

[1] As a result of repeated failures, the locomotives were retired in 2017, and all were cut up for scrap in 2018.