hi all. so happy to be a part of the community!
I recently bought a 2007 honda fit and the back three headrest were missing. I wanted to know can all the 1 gen fits, 01-08, be interchangeable? has anyone tried to replace a first-gen rear headrest with other first-gene ones? Sorry in my English is bad.

 

In the USA, the 2007 and 2008 used the same headrests. As 2007 was the first year the Fit was in the USA, you might want to specify the country...Honda had a tendency to change details from country to country.