vaccum tree

[Baralheia]

I can confirm GM parts departments still carry the correct application manifold vacuum fittings, or at least one that will be compatible. I just purchased a fitting, GM P/N 14069089, that has 5 ports: the top three (small to TVS, top to trans modulator, large to A/C / Cruise) as well as two more large nipples on the lower flange. GM List is $6.42 USD.

You might be able to get the exact part for your application; check with your local GM parts department for pricing and availability.