Like I said, just a general line-up of common/popular double-DIN units that can easily be installed in the FJ.
Not a bad idea for another dedicated thread, but I was hoping to keep this one as a generic "buyers guide" for head units only.
most of those are generic head unit components that need to be considered.
for those that want full functionality:
head units: all single din and double din will work. if you want to keep your steering wheel controls, i suggest you purchase a deck that will allow hard wired steering wheel controls.
dash kits: best kits makes a nice one for a single din. buy one according to the size deck you purchased. they are also available from scosche, metra, and american international
harnesses: all people that manufacture a dash kit for the FJ will also make a harness.
Steering wheel controls: peripheral electronics makes one that allows integration of factory steering wheel controls to decks with both infrared and hard wired remote setups.
*some dash kits and harnesses will fit other applications as well. it may be marked something like scion, but will indeed have the correct part number. be sure to check the numbers though.