I have a 1990 TE $Matic and also the 4MATIC service manual. It is detailed but does not contain any information on how to rebuild the transfer case, valve, pump or differentials. It does contain a lot of info on the operation and troubleshooting of the system, but special tools are required (ie. impulse counters, gauges, ohm meter, plug connectors, etc). I am also part of an offlist (4MANIAC we call ourselves) email group. If your are interested in joining, send me an email (email@example.com).