Replacing Gravity ducts with new duct for new furnace, 6 6" supply's and 2 12" returns. New 97% furnace and new central a/c.
Replace existing furnace with new 80% Furnace.
Install 6 new supply's and 4 new returns for basement, install mail level bath fan and basement bath fan both gbr80 delta fans.
Replace existing 90% furnace with a new one.