Alternative GPS module solution for Nikon cameras: di-GPS Eco Pro-S and Pro-F - Nikon Rumors
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