Unfortunately, due to the proprietary information contained in the CAD drawings, we do not generally release them. There is dimensional information in the user manuals, linked here:
http://digital.ni.com/manuals.nsf/MainPage?ReadForm&node=132020_US
If you absolutely need the drawings, you may want to try contacting your sales representative to see if something can be arranged, but generally the information given in the user manuals is plenty for most customers. To talk to your sales representative, call 1-800-433-488 and they will be able to help you from there.
Regards-
Julie S
Applications Engineer
National Instruments