I'm not familiar with the term "preliminary" as it pertains to MB manuals. I have:
Service Manual, Chassis and Body 126 (comes as one huge, or two vol.)
Service Manual, Engine 617.951 Turbodiesel
Service Manual, Heating, Airco and climate control 126
Maintainance Manual 1981-1993
Technical Data manual 1985
Introduction Into Service manual 1985


The last manual (intro to service), is described as a manual to familiarize the technician with the changes in mechanics for the new models. This may be what the vendor is calling a "preliminary" manual? It is NOT a complete service manual; only changes in service procedure for the new model year(s) is/are covered.

For Christmas/ Birthday/ Father's Day any one out there could get me the Electrical TroubleShooting Manual 1984+. );

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)