I know it's not stock, but I bought one of those battery posts with a knob on it, at a swap meet, for around $3. Best investment I ever made, and now I have them on all of my cars. When you're not driving the car, you just twist the knob a turn, and the battery is completely disconnected. If you unscrew it all the way, and remove the knob, it acts as a simple security device because the car can't be started.