Steven, if you're reading, you got your history slightly wrong. System V got its init handling from Sun's SunOS 4.x. It was negotiated as part of the integration between SunOS and System V which would become the "one UNIX for everyone". Unfortunately for all of us, AT&T really really loved "run levels" and Sun really really liked BSD's way of configuring the system. Which got you the unholy love child you saw in Solaris 2.0 and System V release 2.0.
For the other Sun folks from the systems group who quit rather than submit to the demands, you were right, I was wrong. We couldn't convince them of the error of their ways.
You are correct it was System V, release 4 that merged with SunOS. It was also the release that Sun and AT&T "combined" the BSD init/rc system with the System V init/run-level system.
For the other Sun folks from the systems group who quit rather than submit to the demands, you were right, I was wrong. We couldn't convince them of the error of their ways.