1985 Mercedes Benz 300sd Shifting problem

I have forwarded your link to our resident M/B expert. he should be with you shortly

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https://www.2carpros.com/forum/1985-mercedes-benz-300sd-shifting-problem-vt254465.html

I would be suspect of a couple things regaurding this complaint. First, the transmission valve body may be contaminated or failing due to use over time or irregular fluid and filter maintenance. A severly clogged trans filter could cause irregular shift conditions. Secondly you may have a frozen clutch pack in the trans which is preventing engagement of other gears. From your info I would probably lean towards a clutch pack. I would definatley recommend taking this to a reputable shop as trans work can get expensive if not diagnosed correctly the first time.