I have a used housing body for a D700 that you might be interested in. Its began life as the standard Seacam housing, but I have worked with several machine shops to make modifications that increase its access to a much fuller array of the D700's capabilities than it began life with. The housing has controls that allow you to use the preview and function buttons on the D700. It also has a "clutch" that engages or disengages the manual focus control when you switch the C-S-M control from one of the auto-focus modes to manual focus. The housing also has a port lock, which no standard Seacam housing has. I also have some ports and extension rings available, a Seacam 45-degree viewfinder and a selection of lens gears. I would prefer to sell the housing with a D700 camera body but that is not absolutely necessary.
If you send me a way to get in touch with you I can send you pictures and perhaps we can talk on the phone, My name is Fred. My email is firstname.lastname@example.org