Vacuum hoses are the same size as most small ones on 60-80's U.S. cars (say "vacuum advance" to distributor). I recall 1/8" = 3 mmID. I replaced many on my 84 & 85 300D w/ silicone hose (ebay), purty blue no less, but can also buy in black.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans