Tetrad III is an older, command line version of some of the algorithms contained in Tetrad IV. Its interface is essentially the same as TETRAD II, so TETRAD II commands generally work. Functionally, TETRAD III has one important model not contained in Tetrad II:
Gibbs - An MCMC Bayesian parameter estimator for structural equation models.
The TETRAD III manual is available online. It is best viewed with Internet Explorer.
The program is available for Sun sparcstations or Windows 95/NT machines.
Source code is available in this zip file (4 MB).
Can't find what you're looking for? Occasionally, website updates lag behind TETRAD updates. Check the launcher index for a complete list of available TETRAD versions.
For executable jars, you can look in the download directory.