SF30C

ATSF rebuilt some of their U36Cs and designated them SF30C. The rebuilt units were rated at 3,000 horsepower judging by the model designation. My question is this: when the U36Cs were rebuilt, was the original prime mover retained, and derated to 3,000 horsepower, or was a new prime mover -- for instance, an FDL-12 rated at 3,000 horsepower -- installed?

AFAIK, the original prime movers were derated from 3600 hp to 3000 hp.