Key Updates of the DM&IR SD-M

 

The key updates included the following:

1. 645 power assemblies into the original 567 block (all rated at 1,750 horsepower regardless if they were from an SD18 or SD9)
2. Larger 18-kw auxiliary generators
3. Reconditioned trucks and wheels
4. Electrical upgrade to solid state components
5. Remanufactured D77 traction motors
6. Enhanced air filter system
7. Larger 2,400-gallon fuel tank
8. New transition and dynamic brake equipment
9. Chopped nose

There were 22 rebuilt, with the first (301) in 1979 followed the next year by 302. The steel slump of the early and mid-1980s put a stop to the program but in 1988 they resumed and the remaining 20 were rebuilt through 1991. A roster telling each of their original numbers is at:

http://www.missabe.com/cms/diesel-roster

Also Volume 11, No. 1 of the Ore Extra also had a detailed summary of the SD-M rebuild program. Back issues are available at the MRHS Company Store at:

http://www.missabe.com/cms/content/ore-extra-volume-11