[joyridin']

I have one one of those on my car on the driveshaft and it does a pretty good job of holding it. I wouldn't say it would hold it if I dumped the clutch at 3k RPM, but it will stall the car if idling and you try to release the clutch.

I would think if you want something more than just a parking brake, add a manual line lock to the rear brakes and engage it before you leave the car. I had one of those on a previous vehicle and it would go nowhere without releasing the lock.