I should know this as I removed my folding table/credenza and built a new one, but memories fade. I think the following describes my '85 Sovereign
There was a narrow shelf resting on two supports which went to the floor. As virtually all of the weight rests on the floor, all that was necessary was to keep the assembly from falling away from the wall. This was accomplished by long, "L" shaped aluminum extrusions, screwed into the wall with the addition two large rivets into ribs. The "L" brackets were fitted all along the length of the narrow shelf, and a couple of short ones were attached to the uprights into both the wall and the floor.
The folding table itself was hinged to the narrow shelf described above, not to the wall.
When installing my own unit, I used pretty much the same hardware.