I'm a wee bit confused. This is the speedometer (not working) in my car. http://decristoforo.com/speedo/speed2.jpg
It appears to be electronic.

This is a speedometer cable in my engine compartment.
http://decristoforo.com/speedo/speed1.jpg

This is a instrument cluster from a junker with a mechanical speedo.
http://decristoforo.com/speedo/speed3.jpg

I would like to use it but I can find no access through the firewall to run the cable.

As I have no idea what came first (the chicken or the egg so to speak) any help with this puzzle would be greatly appreciated.

Thanks,
R.J.