RT 3.0.0rc0 is identical to RT 2.1.88

Well, except for the fact that the RT 2.1.x branch is over and done
with. This is really just a release-engineering dry run. But, there’s
a file in pub/rt/devel/ that starts with “rt-3”

http://www.bestpractical.com/rt – Trouble Ticketing. Free.