Are you in for a surprize! 5 1/4" fit in the doors with a plastic adapter.
The rear will not take a 6x9 although they look like 6x9s. They are a
strange Toyota special part that has a 3 screw (vice 4 screw) mount --- a
triangle speaker vice a rectangle. Either a 6 1/2 or 5 1/4 fit with (again)
a plastic adapter. Buy you speakers from
www.crutchfield.com and you get
the adapters included free. I just replace mine with 3 way Sony speakers
and it makes a world of difference. You also get complete instruction for
removing the door panel (inside door handle is tricky) and the rear shelf
panel (have to remove complete seat).