http://www.nikonchat.com/nikkor-tele-lens/

Will it work with my lens?
I have a 70-300mm lens and a Tamron 18-55mm Nikkor tele converter that this work of the two and still autofocus with my D40 http://www.amazon.com/Pro-Optic-Multi-Coated-Tele- Converter-Autofocus-Shutterbug/dp/B000NVO7K0/ref = sr_1_13? ie = UTF8 & s = photo & qid = 1241408482 & SR = 1.13
Working with both, without AF on both. It would be a fine addition to the 70-300, but there was the 18-55 loss time. Do not forget that the opening will also 2x.
Nikon 18-200mm f/3.5-5.6G AF-S ED VR II Nikkor Telephoto Zoom Lens