After much searching online, I found an old email thread with the solution to my Tru64 partition problem. Had to make it recreate all the dev entries.
And this is why Solaris does this automatically after an install is complete and there’s a OpenBoot flag to make it do that (-r I think)
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko