The EMD SD32ECO is a 3,150 hp (2,350 kW) C-C diesel-electric locomotive rebuilt by Electro-Motive Diesel.

It is primarily the application of a conversion kit to an existing EMD SD60-type locomotive.

This involves replacing the existing 710G3A V16 prime mover with an EPA Tier-II-compliant 710G3A-T2 turbocharged V12 engine, with electronic fuel injection.

[1] Starting in 2012, twenty eight Union Pacific SD60Ms were sent to Electro Motive Diesel for this rebuild and are in revenue service as UP 9900-9927.

The SD59MX is remanufactured from the carbody and major mechanical and electrical subsystems of an EMD SD60M "donor".