I have a 1990 300TE 4MATIC. I bought it last year with 115000kms. I find that the hydralic fluid level drops slowly and was told that it be either an external leak (cheap) or internal leak (expensive). There are supposed to be two chambersin the transfer case are the hydralic fluid leaks into the ATF fluid side through a seal and can cause high pressure and heat due to overfill. The lights on the dash are then suppose to light up. I have not had a light "ON" indication so i just filled up the reservior. But otherwise the system works well and seamlessly, I live in Vancouver and it helped on those wet snow days without a hitch. It seems to be very sensitive to wheel spin and you can't even tell it cuts in.