Probably not in a useful way. With a 70-300mm f/4-5.6 lens, adding a teleconverter reduces the effective maximum aperture by 1 or 2 stops depending on the converter. That would push the lens beyond f/5.6 at the long end, and the Nikon D80’s autofocus system generally needs about f/5.6 or faster to autofocus reliably. In practice, autofocus would likely not work properly, especially near 300mm. So even if the teleconverter could be mounted, you should expect poor or no AF performance with this setup.