HVAC help for 70 c10

[Boxxman]

Have a poorly rebuilt 70 c10. I say poorly because I know the guy didn't do all things right with the right year parts and such. I've put an entirely new painless wiring harness in the truck and am looking to get the heat/AC working. I've attached an image of what we have under the dash currently. I've searched many websites and cannot determine what comes after the black box you see in the photo. All pics on websites show ducts coming out of the black box. Mine doesn't have any ducts. Don't have a clue what attaches to what you see. Any guidance would be awesome. Thx.