"The colors are only for factory installers, not service parts."

That's a good explanation. I am familiar with the concept: For example vintage Mustang concours restorers go to great lengths to replicate factory paint markings, stamps, dabs, swaths that assembly line installers used to distinguish part applications.

This V70 is a n/a SE w/B5244S motor. The vacuum line runs from the intake manifold through a module, then passes down under the engine. Maybe a transmission control function? The line shown is the replacement hose, a little fatter than original and all black. The braided line next to it, smaller diameter with a yellow stripe too, is also brittle and must be replaced soon.

Thanks again,