This is what i'm seeing in the BNSF 2007 ETT for that area. I added the frequencies in parenthesis.
Radio Channel No. 66 (161.100) in service Superior to Chub Lake.
Radio Channel No. 85 (161.385) in service Chub Lake to Cass Lake.
Radio Channel No. 76 (161.250) in service Superior Terminal.
Radio Channel No. 33 (160.605) in service Duluth Yardmaster.
Radio Channel No. 36 (160.650) Superior/Duluth Industry Channel.
Radio Channel No. 70 (161.160) in service Grand Rapids.
Radio Channel No. 48 (160.830) MW Channel.
Radio Channel No. 2590 (160.485 / 161.460) Remote Control Jobs
Warren