The D600 simply has the same connector as all the new DX Nikon cameras. Nikon don't make an intervalometer for this camera, but the Chinese do. Basically a rip-off of the MC-36 with the connectors to suit the smaller Nikons.
Find them on ebay for <$20.
http://www.ebay.com.au/itm/TB2-Timer...-/221281441751