'84 240 speedo cable

I decided to replace my instrument cluster from a "pull" yard hoping to get a speedo that works.

So far, so bad.

I have the cluster out, examining it.

I see not one but two openings that look like they want a cable.

One is dead center and I guess a cable under the dash hooks to it to drive the speedo's gears.

But there is another, roughly behind the "80" as in 80 mph. It is white, threaded, and sure looks like a cable threads to it.

But I don't see another cable under the dash.

Am I missing a cable?

Or is the white threaded opening just there, for something else?

I found a short cable loose, about 9 inches long; looks like it ought to fit something. Right now it is on my table.

The white threaded opening protrudes about half an inch from the back of the speedo.

I've checked two aftermarket Volvo books and neither provides a clue.

Can there be two speedo cables?

Allan