Ditto. That looks like a main vacuum feed. There should be 2 plastic nipples on the main vacuum tubing at the plastic check valve. It is common for them to snap off when hands move too carelessly around them. On one of my 300D's, I drilled out the broken nipple and epoxied a thin copper tube to form a new stub. You can buy that main vacuum tube new, but ~$60. I grabbed a spare from the junkyard. Anyway, even when no longer available, it wouldn't be hard to fab the whole system, since just a plumbing job. Just hang onto the metal fittings at both ends.

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