I have a 68 400 model with a split bench/at on the column. Under the dash, on top of the tranny tunnel there is a square of carpet missing. Inside of the square is what appears to be a factory mounted bracket with two screws that look like they held something down. There are also two wires, one hot, at that location. I've got a factory options catalog for 68 which doesn't show anything that might go there. This question has been bugging me for 20 years, any help???