The easiest way to fix it would be to go to a parts house like NAPA or Carquest and buy two 1/8” male pipe fittings to 1/8” or 3/16” flare and a short piece of pre-flared brake line. The fitting on the head will be 90 degree, and a straight one for the AFC. You could also use a piece of plastic hose with compression sleeves (“olives”) and fittings. Cummins probably can order the OEM part but I suspect it would take longer and cost more.