A printing job requires a 72x72" image. I shoot with a D700. Is there any way to get a quality print at that size from a D700?
It depends on a few factors - primarily the print technology that is going to be used, and secondly what the print is to be used for.
The D700 shoots at 4256 × 2832 (12.1 MP), so the largest Square frame you can print at 1:1 pixel ratio would be 2832 x 2832 pixels.
Lets say the print is to be at 600 DPI, which is a fairly standard high quality signage dpi, that would equate to only a 4.72 inch square print. at 300DPI a 9.44 inch print.
so the immediately the answer "No" comes to mind... However...
If you were to print a 2832 pixel width image at 72", each pixel would be printed at 0.645mm width, which is perfectly good for viewing at anything over a couple of meters away. I would suggest that the image is up-scaled 2x or 3x before printing - this will not increase quality but will smooth out the pixels (by making them smaller at print time)