71 K10 speedo cable

[sjarrett71]

I've shadetree mechanic'd most of my life but I have got something I've never seen before so I thought I'd ask. When I replaced my speedo cable, I noticed another very short cable attached to some sort of mechanism with 2 wires coming off it. The longer speedo cable from the speedometer screwed into the mechanism that was attached to the short cable and the short cable screwed into the transfer case. Will someone tell me what the short cable and mechanism is with the two wires attached? Do I need it? What does it do? Did I explain it good enough??