We use to make MightyMounts to fit specific factory crossbars, these have been discontinued and replaced with the Universal MightyMount in most cases. The exceptions are;
MightyMount 32H for the Whispbar / Yakima Through, Flush, and RailBar
MightyMount 39H for use with the Yakima Core and JetStream bars
Attached is a list of prior MightyMounts and which factory bars they fit.