Pics of OEM xB Armrest install?
 

I recently bought an OEM xB armrest (not new) which was supposedly complete but seems to be missing the metal mounting bracket. I found an install manual here:

http://trdsparks.com/install/PTS32-52050-XXinst.pdf

But the photos aren't clear. Does anyone have dimensions / photos / etc. of the wire piece that goes under the seat brackets and under the original rear cupholder bolt?

Go to the features tab at the top of the page and then to the tech section. You will see three threads on armrest installation. Hope they help.......

Yes, but they're for Zeta and JJ armrests, not for the Scion OEM one. Different mounting methods.