I just bought a 78 elky with a 350 and a TH350. It was recently restored.
and I got it for a steal. I have heard of dark knights and royal knights elkys but i'm no sure what those designations mean. The emblems look cool and you can buy them. I just want to know if my elky has to meet any special requirements.

The El Camino Black Knight option was only available in 1978. The next year the option was renamed the Royal Knight. Both these options were in addition to the Super Sport option. See this link for the description and history of the 5th generation El Camino Super Sports.

http://www.necoa.org/modules.php?name=News&file=article&sid=34