I got the sides built and bent using 0.04 sheet for good rigidity. Lined it all up and drilled for the gtr20 first. Then fit the side angles and riveted those with an426-ad4 flush on the inside to not interfere with the gtr45 tray. Then fit and drilled the tray.
Struggled a bit with how I was going to screw the back end of the tray and got the bright idea to dimple the sheet in toward the tray and use a 426 rivet from the inside set nearly double flush. Worked well. I can’t take this assembly apart without drilling out a pair of rivets but it is soundly secured and I can slide it all in and out the front. If I ever use a different transponder I’d probably have to have a different arrangement anyway. Forgive the long screws it’s what I had.
Now to find some shorter fasteners for the gtr20 attach and I’m good!!!!
Still have to fit the front strap brace. Pics when that is done.