Well a warning to all owners of the Nikon 500mm AFS II lens. It appears that the D600 will not focus the lens when used with either a 1.4X or 1.7X extender. I went to Hunts Photo Video both in Manchester, NH & their main store in Melrose, MA. We have now tried 3 different D600 bodies with the lens plus extender combo. Same result- no focus. Not even trying. No extender at all works fine on the body. So it ain't the lens. We then tried a new 1.4X & a 1.7X with my lens & the different D600 bodies & same result. So it ain't the extender either. Combo works fine on my D3s body & the store's D800 bodies. CONCLUSION: NIKON is claiming compatibility of my lens & it is not there. For D7000 owners I believe you will have a similar problem. I tried out a D7000 with the lens + extender & got no focus. Note: both bodies have the same AFS system. I did call a tech rep at Nikon & they have no way of confirming/denying the issue since they do not have a 500mm AFS II on hand.
Bottomline: Sadly I returned the body for full refund to Hunts who should be commended for their excellent service on this.