From what was left of it, my stock setup was 2 crappy speakers, maybe 5" dia, one in each of the rear quarters. The brackets are integrated and they mount inside the rear quarters along the floor.
I suggest ripping it all out and installing a decent 4x6.5" speaker system with a small sub (single sealed 8" or 10"). That's what I'll do once the "stereo phase" is reached. If you must go "stock", you'll be stuck with two speakers and I think you'll have to fabricate your own brackets.
- Greg -