I have a 1990 4matic that is going through fairly large quantities of fluid in the auto trans without noticable evidence of external leakage. I am told by the Mercedes dealer mechanics that the fluid is leaking from the trans into the transfer case, and that the only cure is to replace the transfer case. I have read that a common problem is leakage of the hydraulic oil from one chamber of the transfer case into another, but the problem I am having has not been discussed in this forum (at least not recently). It is hard for me to conceive that there would not be a replaceable seal involved. Anyone?