There are numerous 72 Ford manuals on ebay. Search ebay motors on: 1972, Ford, (shop manual*,service manual*,factory manual*) -truck*, -courier, -radio. This ebay search string narrowed down the listings to 102 of mainly Ford manuals. Use copy and paste as ebay is senitive to spaces and commas.
At Amazon books, searching on "1972 Ford manual" gave 116 listings (not all Ford manuals).
I have usually found buying the complete sets cheaper than buying individual volumes (assuming you want the full set). Yes I have been occasionally disappointed when buying used books on ebay and at other used book stores, no guarantee's.