Chevrolet: 350 trans, chevy silverado, extra tip

Question
Hi, I have a 350 trans that has the normal two gears on the shaft. It also has a extra tip on it and a place to hook up an elec wire. The trans that I took out of my 81 el camino did not have a place for a wire. What is this wire for? Will it work without an elec wire going to it, or do I have to run a wire from someplace? Any info you can give me will be a great help. Thanks, John  

Answer
John
HI well I'm not shure on that wire is but it seems to me that it was for a overdrive gear or a tow/ overdrive switch. I have one on my chevy  Silverado 1500 and it is at the end of the shift stick , the first time i tried it was in 3rd gear and I steped on the gas than hit thaat button, the dash  had a light come on that said tow/overdrive, well i tell you it gave me a good boost.but uses up fuel