Solmeta Geotagger Pro 2 GPS Unit with Pro2 USB Cable, Cable-D (for Nikon D5, D850, D810/810A, D800/D800E, D500, D4, D3-series, D700, D300-series, D2X, D2XS, D2HS, D200) at KEH Camera
Nikon 'forgot' GPS/BlueTooth on D800...: Nikon FX SLR (DF, D1-D5, D600-D850) Talk Forum: Digital Photography Review
JYC N-769/N1 Camera GPS Receiver Geotag GP-1 for Nikon D2X D300 D200 D700 D800 D4 | Eachshot.com
Tutorial Electronics and Programming: Geotagging Nikon DSLR with Vectornav VN-200 GPS (Lattitude & Longitude) + IMU (Compass Heading)