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)
If the raw resolution of your camera is not enough for the intended viewing distance of the 72" x 72" enlargement, and your subject is static, you can apply panoramic photo tools and techniques to stitch together a image of virtually unlimited resolution.