A '76 should have a vertical front grille, exposed door hinges and stamped wheels, not the tri-spoke alloys, horizontal front grill and hidden door hinges.
http://www.range-rover-classic.com/Home/land-rover-brochures/range-rover-1970-s#TOC-1976-Range-Rover-Model-Year---VIN-Suffix-D---Released:-October-1975-
Here's a pic of a 4-door 1976 RRC.
From May 1989, door hinges were hidden, so you'll see some '89s with exposed, while others are hidden. All 90's will be hidden hinges. '94 ROW RRCs/'95 NAS RRCs are one-off (reskinned Discos) with completely different dash (soft-dash).
My guess is that RRC is really mid-1989 thru 1993, as it appears not to be a soft-dash.