Locomotive Phases - EMD SD50, SD60

These phases are of my own making.

Phases - SD50

Phase 1

• Side frame profile: notched
• Blower duct: flat, two ribs, no step up
• Exhaust stack housing: spans 3 hood doors
• Inner dynamic brake housing: angled

Phase 2a1

• Side frame profile: straight
• Blower duct: angled, narrow, step up ("laundry chute")
• Exhaust stack housing: spans 2 hood doors

Phase 2a2

• New handrail stanchion spacing
  • middle stanchions moved forward

Phase 2b1

• Old handrail stanchion spacing
• Inner dynamic brake housing: straight
• Dynamic brake intake moved upward

Phase 2b2

• New handrail stanchion spacing

Phase 2c

• Air reservoir moved rearward

Transition: From SD50 to SD60

• Eight access doors under radiators (rather than six)
• First two hood doors (under exhaust stack) widened
• Blower duct/raised handrail section on left side behind cab moved forward

Phases - SD60

No major production variations.  A very subtle difference between some units is the 4800 vs. 4500 gallon fuel tank, with a slight difference in both the length and the height of the tank.