OMG!!! Thank you Meyerweb! I followed your instructions below, and am now rooted. I've never been so happy over a cell phone. LOL
I used Odin3v1.85 and USCellularGS3CWM6.0.1.2.tar
Then flashed UPDATE-SuperSU-v1.65.zip and the DE-SAMSUNGNIZER_KNOX_REMOVAL_SCRIPT_V1.0.zip
Rebooted with no Knox...