Welcome. Do you just need the AC compressor? What parts are missing? The compressor is pretty easy to find, most of the big chains have rebuilts. Checkers/Shucks/Kragen list one for $116. I just typed in 1970 duster /6 (lot easier to find parts for duster's then older darts), pretty sure they are all the same. AC shop can make any of the hoses and have the small bits (drier's/switches) and there are universal condensers out there.