This probably doesn't help but ...
I had a D3 for wildlife for a very short time, I thought it was terrific to handle on a monopod and I was very pleased with everything about it and with the results.
Bought it secondhand for £900 with 15000 actions and as being in excellent condition but there was a nasty fault in the lcd which could only be seen when direct sunlight shone into it.
It looked like it had burnt inside and there was a large milky white blotch in the centre of the screen - this was not at all noticeable other than with sunlight entering directly.
My money was refunded immediately upon return.
After a lot of pondering since between a secondhand under 6000 shutter count D3X at £1660 and a new UK D750 at £1470, after cashback etc., I have opted for the D750 - having added a grip, another battery, and new SD cards the prices are about the same.
The D3 felt 'natural' to handle as I am used to my D800 with its size and round viewfinder but my head kept saying that the D750 would be the wiser choice technically (and easier to 'move on' if I don't like it).
I have yet to find out !
Good luck with your choice.