Mine came in today. A very easy fix. Think is supposed to be 19mm but 3/4 inch worked fine. The connector on the vac pump was hard to break loose. Almost banged a knuckle. It took a while to unscrew because you don't have a lot of room. The connector on the brake booster appears to be plastic so be careful. Remember lefty loosey- righty tighty.
I removed the old hose assymbly, ran the new one through the firewall to the booster. Finger tight, then to the Vac pump, again finger tight. Check the position of the grommet that connects to the filter and the connector that connects to the shut off hose. All looks good. Tighthen the connectors with the 3/4 inch wrench.
Took for a test drive. All works well.

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92 300D 2.5L OM602 OBK #59