First of all... the gaskets cost about $ 8 or so for the set. The Solenoid can be had for about $40. I'll be more than happy to ship you both things for $50.
That dealership is ripping you off. Avoid them.
The lack of OD is more than likely one of about 5 (or so) things.
1. There could be some electrical problem which is causing the PCM (computer) NOT to be telling the transmission to shift into OD. It could be a bad speed sensor, or some other input. In short, under this scenario, you don't have OD because it's never being commanded (since it is a computer controlled shift). [Probably unlikely, since most of those would also affect TCC lockup as well.]
2. You could have a bad solenoid. [Possible]
3. IF there is a screen on the 3-4 shift solenoid it could be plugged up.
4. The valves and things in the VB that cause the 3-4 shift could be stuck or sticking [HIGH probability] or the gasket could have a leak [unlikely on the A4LD]. The vb could be loose. [low probability]
5. You could have a servo leak in the OD servo which does not allow suffient pressure to actuate the band. Or alternatively a broken band. You'll know if it is the band when you pull the pan.
I probably should add a number 6: an OD band so badly glazed it won't apply and hold. [unlikely or you'd be burning up the tranny IMHO]
You might want to look at the A4LD Valve Body Rebuild Diary and think about trying that... check wiring, connectors as well. When you pull he pan to do the VB you'll be able to rule out the band being broken.
Another case where the Rotunda Trans tester would be worth its weight in gold. (see PS below)
Good luck and keep us posted. If you want those gaskets and the solenoid let me know.
It's difficult to know which of these it is without more, some of which would almost have to be hands on. Given the recent rebuild I am going to guess it isn't a bad servo or broken band.
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I came back to this reply, and thought mabe it would be helpful to tell you what I would do if this were sitting in my garage. First off, I'd drive it and watch the RPM's and shifts... verify your concern and try and insure I have TCC lockup. (So I know if I have 2 problems or 1. Also if you had neither TCC lockup or 3-4 that points VERY strongly to electrical problems!)
Next I'd hook up the transmission tester to the transmission and bench check the solenoids. Assuming they tested out ok, I'd do a test drive and see if the tester can command and get OD. If it can, then I know the problem is upsteam of the transmission - PCM inputs or harnesses. If the tester cannot command OD, the next step is to hook up a pressure gauge and watch the pressures in a test drive. I'm especially interested in knowing what happens when I should be getting 4th. Assuming nothing sinister shows up here, then then I know I am going to pull the pan. (low pressure would lead me to continue to suspect the OD servo - but I'll not jump into trying to replace it yet as THAT is a MAJOR PITA, and other things could cause low pressure besides just the servo.. it would just stay on the radar is all if pressure were low.)
Next I'd check that the adjusting screw for the OD band hasn't somehow backed off (I could probably do that sooner, and maybe should do that first... just crossed my mind, but this is kind of stream of thought here). Assuming that is ok, I'd get ready for the ATF bath and drop the pan. I'd check the pan for band parts and metal filings or chunks. I'd visually inspect the band location and that the actuator and anchors appear ok (a little tough but you can get a pretty good idea). Assuming so far everything is ok, I will remove the VB. Since I have already resistance checked the solenoid and click tested it, I am pretty sure it is ok electrically. I'll remove the solenoid and check for a screen. If none, I'll visually inspect the VB to see if any metal slivers have gotten lodged in it. and if not, then I will rebuild the VB. and reassemble. If the test drive does not show a fix, I'd pressure test it again and if I have a low pressure in OD, NOW the servo.
Somewhere in that maze is our likely culprit methinks.
PS. I do loan a FORD rotunda trans tester... they are a pricey gadget (about $1000 new) so I require a deposit ($300 - waived under certain circumstances), but in the end all it costs you is round trip shipping - Probably $30 to 40.
