Cross cabin bar
If you are referring to the lateral bracing bar that runs the full width of the cabin and (also) supports the front seat backs - this is a standard part of the structure and not installed specifically to support the 4-point harness. Mine has the standard inertia reels plus this bar.
The optional non-RHC leather trim includes some neat rolls of padded leather around this crossbar.
Blighted serials? I dont know but I bet your maintenance centre will have a pretty good idea...?? They will know only too well when the corrosion problem started. If they are like mine, they will be frustrated to hell at dealing with irate customers and at the same time not enjoying the support of the manufacturer.
Its time RHC stood by their product, admit that they have a problem and deal with it in the proper way.
Here I am singing their praises for a fine machine and yet have had to shell out a considerable sum of money, well within the warranty period, to put a nearly new aircraft back in the condition it should have remained in for many years, not just one.....!
JB