Dee, for G's sake avoid the 70-300 Nikkor G lens. Cheap and nasty in my exp and above 150mm, useless. No contrast, saturation, sharpness, speed etc. etc. A very woolly piece of kit. Mine was a dreadful mistake and sits unused in a box. If weight isn't too much of an issue and if longer lengths are needed, lookat a 50-500 Sigma. On the D70, it is heaven. If you have to bolt a Nikon 70- 300 on the end, the D version is far better, though still only average.
Conan