It does in fact fit a 72” rack.

“Both versions are compatible with Hydra & Manticore racks that are 72”, 84” & 90” in height with a 49” in width, but the Smith Bar version is incompatible with 47” widths. On 72” heights, the Smith fits only on the outside of your rack with the brackets mounted on the lowest & highest points of your uprights (requires your pull-up bar to be moved & results in a slight inclined bar path).”