Does the camera have to be modified to use the VG-D70 grip?
Absolutely not! The VG-D70 can control any D70, out of the box. The D70’s IR shutter release has some limitations (no half-press, 15 minute shut off), but it works fine for most applications. If you really need the half-press on the vertical shutter release, there has to be a direct connection to the camera.