Just read this:
Speakers
The factory speakers in a Skyline were 6/6.5" (?) at the back, and a weird rectangular shape at the front. However, you can fit 6.5" speakers in both locations easily, you may need MDF spacers for clearance but it's a fairly easy job.
6x9s will fit not so easily, but still doable.
What do people think - will 6x9" fit - or should I get a set of spits for the front and put the 6.5" in the back?