Let me first say the the local MB dealership parts dept. did not know the answer to my question, and asked me to bring my car in.

Dumb question: I have a 1983 380 SEL (W126) and I have some fuel and rear brake lines I would like to have replaced. My question is: What is the "3rd" line?

metal fuel line #1 = supply line coming off the fuel filter

metal fuel line #2 = return line to the tank

metal line #3 goes to a plastic part the size of a golf ball attached with braided lines at each end of this part (which is falling apart)

metal brake line #4 is the rear brake line

these 4 lines run millimeters apart, for the length of the car.

Thanks!!

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Scotty P.