Ask Professor Google for a vacuum diagram for your car. You need to know what the lines go to. Vac starts at the vacuum pump and branches. You can disconnect and plug and/or use a hand pump on the individual circuits. Having the diagram will go a long way towards explaining which lines hold vacuum.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.