Alternative GPS module solution for Nikon cameras: di-GPS Eco Pro-S and Pro-F - Nikon Rumors
Nikon 'forgot' GPS/BlueTooth on D800...: Nikon FX SLR (DF, D1-D5, D600-D850) Talk Forum: Digital Photography Review
Sevenoak Electronic Gps-n1 Cable For Camera Gps For Nikon D200 D300 D300s D700 D800 D2xs D2hs D3 D4 D3x D3s - Photo Studio Kits - AliExpress
Nikon D800/D800E - still no built-in GPS » foolography
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