Currently there's no SkyPriority PreCheck line at South: you can pick either PreCheck or SkyPriority but not both, and this has been the case since the North and South checkpoints were created with the SkyPriority check in area moving from the center of the terminal to the far South end, near the South checkpoint. Before that, IIRC checkpoint #4 just to the left of the SkyPriority counters was the wonderful one that at one time was exclusively for people with *both* SkyPriority and PreCheck, and then it was reconfigured to include PreCheck without SkyPriority too and was a mess forever after.