Yes, that's pretty clear. Unibody cars without a full frame can have 6x6 plates welded to the floor, or a plate on top and on the bottom, sandwiched by bolts.
What I'm trying to find out is, can the bars pass through a hole in the floor and be welded to the subframe connectors instead? Adding subframe connectors does not constitute a full frame according to the rule book, so I'm guessing "no".
