Well, I took pics today, but I'm having trouble uploading them from my phone (I HATE "smart" phones).
I've learned quite a bit from toady's installation of the blank today between wife's office and the dinette area.
First, drill holes smaller than the head of the screws I'm using to allow for some play. Screw holes are not consistent distances on HF.
Second, getting the upper lip to successfully slip in between the roof and ribs is a bit tricky and tough but doable.
Third, there's quite a bit of preparing to do before installing the blanks. Pre-drilling holes, priming the blank, testing the fit, using red thread locker to secure the screws, and on and on and on.....
However, I'm that much closer to getting insulation, heat, and A/C going.
Pics as soon as I can get them out of this