Steve,
They primarily use the 160.215 (AAR 0707) road channel of their host railroad, the Fort Worth & Western, for all operations. To cross the UP Choctaw Sub and run two miles on Choctaw Main One to FWWR Hodge Yard they contact the UP Terminal Dispatcher on 161.280 (AAR 7878); and then they use 160.650 (AAR 3636) to talk to BNSF DS22 to get permission to cross the BNSF and UP at Tower 60 before entering or leaving the Stockyards.
Ken Fitzgerald