So I want to install a b&m shifter in my 82 trans but there is an additional cable attached to factory shifter. Tried to google what it is, goes to, purpose it has, and nothing. I just get pages of hurst b&m summit and jegs websites and just as many of gear shift cables. So can anybody please, for the love of all things holy, please steer me in the right direction? 

I have an 86 Trans Am. I have the factory manual at home, I can look it up. My educated guess is it goes to the steering column - either for the neutral safety switch or it physically rotates the steering column between P R N D 2 1. I will let you know what I find.

A lot of older console shifts actually rotated the steering column. It was the steering column that was actually connected to the transmission cable/linkage. This way GM could use the same transmission linkage on a car that could have either a console shift or a column shift.