"exactly wher ere the tweeters on the dash?"

A lot of speakers these days are actually two different speakers in one.
Inside the main body of the speaker is a "tweeter" for the high end sound.
On many models these tweeters can be mounted separately.  Tweeters are also
sold separately as components of a larger system.  The problem with these
tweeters is they are not recessed like the factory speakers and actually
protrude beyond the speaker mounting surface and interfer with the dash,
window crank, or both.  Some people deal with this by mounting the tweeters
apart from the main speaker and then they have a flush mount speaker.

While we're on the topic...
I recently picked up this Kenwood Sub/amb combo.
http://www.crutchfield.com/S-2B4j5cftiEf/cgi-bin/ProdView.asp?search=kenwood+sub&i=113KSCSW1
Does anyone have any suggestions on mounting locations for an 87 Westy?  I
don't want to put it under the rear seat for two reasons.
Fist, it's already packed under there.  The rear heater takes up so much
space I don't want to give up any more.
Second, on long trips it's nice to turn the fader up front so the driver can
have music but passengers and dogs can sleep without boom, boom bass under
them.
I was hoping there might be an option somewhere under the dash, but have
never had my dash apart to explore options.
Anyone have any suggestions?  Ive heard there is some space above or behind
the glove box, but would prefer to center as much as possible?
What's immediately behind the center plastic piece that goes to the floor?
Thanks,
Mike