Where can I purchase these over the counter. I called a few auto stores and I was being told that the fuel lines that they carry didn't have any specification. For the most part they said no. I'm looking to replace the rubber fuel lines in the engine bay leading from the hard lines to the pre heater. There are 3 lines that are pretty close together. One of them is leaking. I intend to replace all 3. 1991 300D 2.5.

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1995 E420 152k
1991 300D 2.5 348116 daily driver
1992 300E 2.6 196k-work in progress(head gasket)
2002 BMW 745Li 93k