Here attached the patch file for clip12 primitive that provides connectivity to 16770...
Note that AFAIK 75973 has not been added to LDraw yet but 30033.dat is close enough.
And then... now that Sergio is no longer among us to maintain SR3D builder I'm afraid that its usage will be more and more problematic. Even if a few people know how to create connectivity patch files, who will do that and publish them? And some connectivity is built in code, not in patch files
The other problem is parts images, I was never able to generate them using SR3D built in tool (though this can be done with other tools such as LDView).
So... I now changed my main LDraw model editor from SR3D to
LDCad, and I must say I don't regret it. Among huge benefits compared to SR3D I can quote the excellent submodel management, better image quality, very good flexible part generation (fully compatible with other LDraw tools). The only area where SR3D still has an edge is animation. LDCad animation is very powerful but needs a lot of work, whereas SR3D animation "just works" if you have parts correctly placed. Of course this may change...
Another very interesting feature of LDCad is that in addition to connectivity mode you can use grid mode to place parts - so a new part that doesn't have connectivity defined can still be used relatively easily.