I plug the vac off and had clunk upshift/downshift so I guess it is needed both ways....?

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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

Cho - not so. It is designed to upshift with zero vac. That is why it bleeds off vac when you hit the gas. Immediately the vac should go to zero. It only needs vac for the downshift.

You may have a combination of problems but clunk on upshift would not be from lack of vac.