Charm.li should have the procedure for replacing it. It's a bunch of work. I would hit up a junkyard for a repalcement piece, and you'd also gain experience w pulling it.
Depending on your fabbing skills and how you want the truck to be, you could also design/3d print, or cut out that mounting area from a replacement hvac housing, trim off that one remaining post so it's flat there, and then melt/glue/screw the mounting area to your housing.