Les,
I refer once more to the drawing I posted on the first page of this thread.
In the bottom-right corner you see everything you need to know about the RTG-side of the attachment. Each pair of RTG has a triangular plate between the single units, one corner faces towards the HGA. From these plates, 3 'V'-shaped struts connect the RTGs to the struts (3 for each pair of RTGs):
These struts slide out of mounts located around the Instrument section when the S/C rotates. They initially reach through the S/C adapter and thermal blankets. You can see their location on the unfolded side view of the drawing sheet (here marked with arrows):
Note that the struts of one pair are closer to the Instrument Section housing than the other so that they lay in seperate plaines (otherwise they would collide when stowed in launch configuration). The orange arrows mark two attachment poins which are hold by struts around the star tracker (not directly on the instrument section). The two green arrows mar two other points which were probably only present on test equipment.
I hope this answeres your question.
Thorsten