Here is the Pioneer Unit I just put in:
http://www.crutchfield.com/p_130P4200UB/Pioneer-DEH-P4200UB.html?search=4200UB&tp=5684

So far I love it. The bonus of having the USB port is that aside from using
it for an MP3 player you can also just use a thumb drive in there. The unit
will read MP3 and WMA files. Works great and I can now carry A LOT of music
on a very small device. Plus this unit has the front AUX port as well.

This unit fit fine - however the stock metal braket under the dash has been
removed from my bus too. Not sure it would have fit with that bracket there.

I agree with Loren - speakers are the key. I just installed these in the
front:
http://www.crutchfield.com/s_065SC50/Boston-Acoustics-SC50.html?search=SC50&skipvs=T

They sound great! I love Crutchfield but I do have to admit I found these
speakers on EBay brand new for half the price Cruthfield is selling the for.

Once I figure out how I am going to mount rear speakers (I have a hard top
'85 GL so not cabinet) I plan on getting the matching Boston Acoustic
non-component speakers for the back (SC55 is the model).

I also found some decent shallow mount smaller diameter subs - one a 6" and
one and 8". I may add something like that later. I don't need to thump but
would love to have better Bass sound at highway speeds.

I think speaker baffles are importatnt too - they are inexpensive - improve
your speaker sounds and keep the speakers clean as well.

Now just to figure out how I am going to deal witht he window cranks hitting
the speakers :) I've had some good suggestions from others here but nothing
that will really work for me at this point.

--
Thanks,

Jeff
'85 GL (Gertie)
'90 Carat (Grover - the noble parts donor)
'78 Bus (Melissa) Patty's Bus