According to Ford, the service replacement for 1966 is 380726-S, which is the same clip used on the V-8 fuel line bracket (9180, not serviced) and the fuel line to valve cover on an I-6, ref ILL Sec 90 pg 3. Others have stated the I-6 clip is different. It may be, but 380726-S works.
Jim
380726-S is the factory installed clip used on 1967 170 and 200CID engines - ref AM00157 pg3. The only drawing I've found of that clip is in "Ford Standard and Utility Parts Catalog, July 1966", pg 32. What is shown there is not the same as what I've removed from 1966 289CID engines.