How it went, for those who want to try this at home: First, Napa had one of these for $150 where the dealer wanted $250.  Also, as the dealer wanted close to 800 bucks for the full job, I opted to try it myself first -- After all, I could always take it to the dealer later and pay the $800 bucks then.  Hey, back in 1987 when I worked behind a parts counter in Tucson (student job) I had an 8 hour seminar on auto A/C. :-)  Since there was no refrigerant left in the system, and r134a is not the toxic and environmentaly dangerous chemical that r12 was anyway (go read the msds sheets if you don't believe me), I didn't need to have the system evacuated first.

Tear down to get to this part is an ugly mess, but doable if you're patient.  The steps in the Haynes manuals are poorly laid out.  I found the reference data on ALLDATADIY.COM to be better, but still pretty poor in some respects.  A combination of both helped.  Of particular note, the diagrams and snapshots in both are too limited and frequently do not show clearly the location of fasteners to be undone in a way that a mortal can use.

The entire dashboard assembly, guages, steering wheel, and steering column had to be removed entirely.  If you're going to do this, label the trim panels by side and use an arrow to mark which part is forward facing.  I also like to tape each screw to the panel at the point it was removed.  This sounds tiresome, but adds very little time to the job and saves a huge nightmare later.  In my case, the entire thing went back together without  a single left over screw or fastener.  Just in case, I did take plenty of digital pictures at various places just in case I needed to refer back to how something went together.

When you finally get the dash assembly out, there are still 4 (count them) nuts on the firewall in the engine compartment (at least one is hidden by being used to also hold a coolant line bracket to the firewall -- the Haynes and AllDataDIY diagrams are singularly unhelpful at finding them) holding the heater/ac unit to the car which must be removed to pull the unit out far enough to open the top and remove the coil.  If you're not changing the heater core, you do NOT have to disconnect it and drain the system -- it is possible to pull the assembly out far enough to pull the lid open enough to change the evaporator coil without disconnecting the coolant lines from the heater core.   That said, you'd be a fool not to change the heater core while you've gone to all this trouble.

Other notes:

O-rings do not come with the new evaporator coil, they are part of the procedure for changing the expansion valve.  Yes, that's moronic, but its true anyway.  I even asked at the parts store for any "kits" that go with the part to make sure I'd have them.  No help.  I'll probably end up having to do that small part of the job at the firewall again as a result if the old ones don't hold.

Do not attempt this unless you have a pretty full toolbox.  You will need some special tools -- "star" bit security screwdrivers of various sizes, a steering wheel puller, a refrigerant line quick connect tool, and of course r134a guages.  I recommend also finding plenty of patience, a few good but small flashlights, some quite music, and at least one full day to your self with the kids and wife out of town.  ;-)