Dan, IIRC the 73-4 standard headliner is 4 bows, the 71-2 is 6 bows, the 71-4 sunroof 3rd generation B bodies use a 2 bow headliner, the 71-2 cars have these monstrously heavy solid urethane bolsters that surround the sunroof cassette/tub opening that get upholstered in headliner mat'l, the 73-4 hand crank sunroof cars have a perforated fiberboard that clips to the sunroof cassette/tub that the headliner tucks onto and is retained with windlace, the A bodies are very similar

There's also a perforated fiber board for the sun roof sliding panel that gets upholstered as well....IIRC the hand crank cars also have a "privacy" panel that slides by hand from the cassette/tub if you don't want to close the panel but want some air flow, IIRC that panel is perforated and covered in a very thin vinyl almost decal type covering and colored to match the headliner...

I don't generally deal with the hand crank sunroofs, just the electric 69-72 models

Mike