I use a piece of 6x6 wood I cut down to an angle, I put it under the tire with the angled face down. I've tested it under my deuce on my sloped driveway with no parking brake, and then in reverse. I 'could' have ran over it, but that was more than it would ever suffer normally. I tied a nylon strap around it to make it easy to put out of the bed, and from under the tire. I personally wouldn't leave a deuce in gear. It will start in gear (I dont know about low range xfer case), and if you happened to forget, or if somebody else starts your truck for some reason, it will go forward despite that parking brake. Also if a deuce gets bumped somehow, say rear-ended?, a deuce can start and will go forward.