Mystery Speedometer fm Hershey Swapmeet

[lizhuo]

I thought I got a bargain speedometer from the swapmeet. I've got an '82 911SC with an 85mph VDO speedometer that has 9 pin connections (I checked this after purchasing the speedometer). There were no partnumber markings I could find.
I picked up a 180mph VDO speedometer that only has 5 male pins and two holes where something can plug in. There is also a yellow knob. I can faintly see a tag on the side with the following numbers on the 180mph speedometer:
467 204/010/082
964 641 517 00
K?6519 Imp/Meile
12V
It looks like a VDO serial number K040893.

Might I have gotten a 911 C4 speedometer and can I even use this thing? If not, is anyone looking for a speedometer, cheap?

If I can use it, what is the pin-out for the 180mph speedometer? What pins should I connect from the existing wiring? I've got the SC wiring from the Bentley's.

On the plus side, I did buy a few items that seem to work (a heater lamp bulb and a trunk lamp bulb). My family also enjoyed visiting the chocolate factory and Gettysburg outlet stores.

Any suggestions appreciated.