Sun GKS device drivers?

[ray at dsiramd.dsir.govt.nz]

What ("3rd party") device drivers, apart from the stated HP-GL and
PostScript, are available for Sun GKS?  Apparently Sun Consulting Services
have some information, I have asked my Sun salesman to inquire.

Alternatively, is it possible to generate and add one's own device drivers?

I am interseted particularly in X-11, Tektronix 4010/4, Tek 4105/7, and
(possibly) VT240 (DEC Regis).

The environment I am considering is SPARCstation 1/Genstat V (which has
an interface to Sun GKS).