Railroad Archives Online
- CollectionD0288 - Terence Wahl Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3002 - Diesel Locomotives
- 4 more...
- ItemTRWahl0262 - Northern Pacific Diesel Locomotive 215, Arlington, Washington, undated
- ItemTRWahl0263 - Northern Pacific Diesel Locomotive 217, Arlington, Washington, undated
- ItemTRWahl0371 - Northern Pacific Diesel Locomotive 283, Bellingham, Washington, undated
- ItemTRWahl0372 - Northern Pacific Diesel Locomotive 283, Bellingham, Washington, undated
- ItemTRWahl0639 - Northern Pacific Diesel Locomotive 6504, Seattle, Washington, undated
- ItemTRWahl0640 - Northern Pacific Diesel Locomotive 5400, Seattle, Washington, undated
- ItemTRWahl0671 - Northern Pacific Diesel Locomotive 426, Seattle, Washington, undated
- ItemTRWahl0679 - Northern Pacific Diesel Locomotive 555, Arlington, Washington, undated
- ItemTRWahl0698 - Northern Pacific Diesel Locomotive 259, Bellingham, Washington, undated
- 16 more...