Looks like you have a B pillar from a coupe or convertible and those two holes - hold part of the window mechanism in place (to the body)
Those two holes would have two zinc/cad bolts holding an adjustment plate much like you will find on the top inner surface of the door - all body types
Notice also that the slot at the top (in this case for the window not the little quarter window pivot in Brian Conway's example.
Someone much have used a donor car (different body type) if this is on your Mach I as shown in your signature