There is enough room behind the panel with the headlight switch. The knob itself has a small nut that screws onto the knob shaft, this will go on the outside of the dash, IIRC there should also be another nut for the inner side of the dash. The nut will hold it in place, but better yet use some epoxy resin to glue it on the inside so it wont spin around the shaft if it were to ever come loose.