I've been with Nikon a long time - long enough to remember when FM meant Fully Manual and didn't have a 2 attached.
Yesterday I was pawing around in a place I've not been for awhile and found:
= Vivitar 28mm/f2.8 = Vivitar 75-205mm/f3.5-4.5 Matched multiplier (which I can tell I bought in about 1968-70 because of a number I engraved on it when I was in the Navy.
And what I wonder is whether I'll hurt my D7000 by trying to use these lenses. I know they're manual everything, and I have a Tamron 17-50 so the 24mm isn't really necessary, other than it's a prime, but the doubler would be cool to try on the 70-300 zoom. I haven't even yet check to see whether they'll mount. Scared something electronic will mess up and then I won't have a camera.
As stated above, Do NOT Mount either lens or the TC on your D7000! Any lens made before 1977 will be Pre-AI and can Not be mounted on your D7000 without being modified to AI spec. While I suspect David White would convert them, it wouldn't be worth it. Given that the 70-300mm is f/5.6 adding a 2X TC will get you to f/11 which means the viewfinder will be very dark making focusing very difficult even in bright daylight and impossible in poor light. Good Luck and Enjoy your Nikons!