Well, Navtecs are "backwards" compared to most common turnbuckles, in that, instead of two screws coupled by a body in the middle, they're two "bodies" coupled by one screw in the middle, but, essentially: Yes.Yes, they are C500s.
Maybe I'm making this harder than it should be. Is it as simple as sticking a screw driver in the turn buckle and unscrewing?
One item that Navtec does recommend replacing after 10 years of use or 40,000 miles (whichever comes first) is the turnbuckle screws. With the stress concentrations due to the threads, cracks could be forming that may not be noticed until they fail. The screws may last for many additional years, but it is much cheaper to replace a few rigging screws than to replace a mast and all of the rigging.Contact Navtec for further information.
These pins can be loose but can't fall out -- the diameters of the pins where the toggle bears is larger than the diameter of the pin where it passes through they eye on the turnbuckle.
I found many disturbing lose pins on my Navtec parts at the red allow which could have fallen out