KR-9600 Misc Part - Where does it go???

I've had my KR-9600 apart for about 6 months and I can't for the life of me remember where these 2 matching rails go and how they mount? They are the right size to fit where I'm showing, but I don't think they just "float" in the corners.

Somebody that has taken apart their KR-9600 recently is bound to recognize the 2 elongated U shaped rails with the circle holes on one side. It was dusty in the middle on the inside of the rail so that part was likely facing upward (which corresponds to how I have it setting in there.) Maybe the bottom cover squeezes the 2 rails into place? I should have taken more pictures!

Between the outer edge of the heatsink and the bottom plate. The'll only fit in one way, and they're hard to keep in place while putting the bottom plate on (so I sometimes use a small piece of tape to hold them in place till I get the bottom bolted on).

I believe the holes face up, on the outside edge of the heatsink. Neither pic you show is correct. Keep at it, you'll know when you get it.

Actually, that 2nd pic shows the proper placement...it's the only way it can go in there and be flush to both corners so that the cover and bottom can attach properly. Any other way and one of the edges protrudes out a bit. With it turned either way there's 2 rotations to try from front to back and 4 rotations around from side to side for a combination of 8 possible orientations. I was pretty sure I was in the right area due to the length being just right, and if I can't figure it out from there I might as well give up! haha

Thanks!