SunOS jawdropped 5.5.1 Generic_103640-29 sun4u sparc SUNW,Ultra-1
SunOS gobsmacked 5.6 Generic_105181-39 sun4m sparc SUNW,SPARCstation-10
Ouch! I thought I had long seen the last of such hardware or Solaris versions.
Now, Solaris has excellent binary compatibility. I have some old SunOS 4 binaries from the 1980s that I use on a daily basis. So I'm expecting to be able to take a lot of what's present and simply move it onto new systems.
I'm also planning on using Solaris Containers to help make the transition easier. I would much prefer to do a proper move of the application to a newer system, but that takes time. The advantage of the Containers approach is that you can lift up a working system lock, stock, and barrel, and migrate the whole lot in one fell swoop - otherwise it can be quite a lot of effort to cleanly extract an application from an old (and usually undocumented) system.
Unfortunately there isn't a Containers implementation for Solaris 7, 2.6, or 2.5.1. So those have to be done the hard way.