All '66 Darts use the same trunk lid except the station wagon. Moldings and emblems might be different between models however, so, you may need to drill or fill holes. No other year or model is the same.
All the mounting brackets are the same '64-6 273 (and even poly 318's) A/C and non-A/C. The adjustment strap is different between manual trans and automatic for some reason. Not sure what the difference is or why there should be one, but, they have different part numbers in the factory manual.
Looks like it's actually a '64, but, same V8 changeover parts will work. I can't seem to link it for some reason. Just look up Los Angeles Craig's list and enter '64 Valiant in the search box.