[atoman]

you can try to check with a good tranny rebuilder, if you have one around, (and i don't mean aamco or the like) if they can overhaul it or replace it with a rebuilt unit.. (but it's not user serviceable)

the main problem with awd on these vans is that many units go unserviced until there's a problem / symptom...
even though not many were manufactured, I'd suspect they use gears and hard parts that are probably available / used in other powertrain applications...

 

[atoman]

as I see it, AWD system should be serviced at the same time as the ATF oil & filter change.. (but that's just my opinion)
RE: schedule, in non severe schedule it must be done before 5years / 100 Kmi.. (in severe, I think, it's before 3year / 60K)

 

[atoman]

Does the rear diff have drain/fill plugs? Does it take regular gear oil?

yes and yes (80W90 for differential only, everything else ATF+4)
http://forum.chryslerminivan.net/showpost.php?p=134897&postcount=2

 

[atoman]

I'm not sure this is going to help you.. but take a look at getrag site..
http://getrag.de/en/258

They do have a US subsidiary.. (I doubt they do any direct sales..)

GETRAG Corporation

Address
GETRAG Corporation
GETRAG Engineering Center
36200 Mound Road
Sterling Heights, MI 48310
USA

Fon +1 (0)586.939-7700


* Development and marketing of axles
* Employees: 50


Management
Friedemann Strasser
[CEO]


GETRAG Transmissions Corporation

Adress
GETRAG Transmissions Corporation
35533 Mound Road
Sterling Heights, MI 48310
USA

Fon +1 (0)586.620-1300

* Seat of the management
* Seat of the central departments and the product development for GETRAG Powershift®
* Associates: 100



Management
Tobias Hagenmeyer
[President]