duster floor pan piece needed

i am woorking on a 1970 duster ,i am looking for a piece of the floor pan that is the rear pan under the rear seat , the piece i need goes from the rear seat front mount towards the front of the car and gets spot welded to what would be the rear floor pan on the 70 duster i am working on this is the bottom of what looks like a dead air space behind the vertical pan portion of the rear pan where your feet would go in the back seat , this is not a whole pan its the front portion of the under the rear seat pan. i think other year duster pans will also work ? please let me know thanks ed