Looking into how the supporting strut needs to be placed, I noticed that there seems to be some variance in the way the part is mounted. I was sensitive to this, as on my car the vertical flaps were mounted inward- steeering me towards some checks.
So I checked a bunch of resto threads, BMW tech Manual, NOS parts, and cars, and I spotted another difference.
In 3 instances of the checked pictusres, the edges of the supporting strut (not the vertical flap) are facing inwards , and on 17 they face outwards.
The Tech manual shows the edges pointing outwards as well as can be seen in the post above here. So you'd think OK, clear - whoever placed these parts with the edges to the inside needed a coffee.
But then this:
BMW NOS parts, with PN sticker still on them. (Still available through kleinanzeigen for 300 euro btw)
Clearly a left and right part as the vertical flap (used from a certain year onwards during production) is welded onto it.
The large flat section of both parts are actually identical pressings with just the flap welded on the other side.
So if these were welded in, the edges would face inward on the right side, and outward on the left side.
Left hand part on left (below), and RH part on right below. Notice how they are same stamping, but upside down?
Here you can make out the PN....82 which is the RH part.
Ergo, whichever way you weld em in, there is a BMW driving around in a form that BMW have build themselves.
I'll just follow the most logic, and weld em in so the flanges point outward, like the Tech manual and the majority of the cases i checked.
I guess that also matches the notches at the top of the small funny triangle plate that slides over these:
