Union Pacific has rebuilt 129 of their GP40's and GP40-2's into
GP40N's at their Jenk's shop. These units received a microprocessor control system to increase adhesion, control options, and extend the life of the locomotive.
CSX has rebuilt only one GP40-2 locomotive, numbered 6041 (originally
BO 4141), into a hydrogen fuel cell locomotive in collaboration with
CPKC on April 16, 2024. The unit's road number is 2100, and classified as
GP38H2. The railroad also rebuilt a handful of GP40-2 into GP40-3s, which features new cabs, new electronics, and other internal differences. == Preservation ==