Part # HAC-18_1967 Vacuum actuator with stud- metal
My son did alot of research and found these. They are not exact replacements, but can be made to work.

It is alot of work to replace them, but my air now works great.

HAC-18_1967 vacuum actuator.

You need 2 of these-need minor modifications. They mount the same and the housing is metal. vacuum nipple is smaller. I cut the nipples off my old ones and glued to the smaller metal nipple so the vacuum hose would attach.
You have to remove a small metal stud and use the hole where the stud was and use a new slightly bigger diameter screw. Grind off one side of the stud and push it through the hole.

gm part number 1996686

You need one of this-looks the same as Volvos but mounts differently. You just have to modify the original mounting point on the cover the bellows attaches to. One of the nipples points in a slightly different direction, but after mounted your existing vacuum hose will still attach.

Also since you will see the heater core after removing the cover that the bellows mount to - DEFINITELY REPLACE THE HEATER CORE.

You should be able to google the part numbers and see pictures.

Jimo