Years of wear on my trucks shift lever & where it goes in the steering colum has allowed me to remove the pin holding the shifter to the collar on the colum with my fingers--and I can stash the lever in the glove box and lock it...I've only done it a few times when I had to park in a "bad" neigborhood...
I also have one of those things that hook around the brake pedal to the steering wheel with me,(the "Club")-but never used it to lock them together--I have used it to ward off a few thugs once who approached me one night though!..
Both of these "security" devices could end up putting you in more danger,if you had to hop in the truck and make a speedy getaway--by the time you got the "club" off or the shift lever back on,you'd have been dragged out and beaten by then probably.
When you have a 6.2 diesel that is a moot point anyways,no speedy getaways--by the time you cycle the glow plugs,and hope to hell it'll fire up on the first attempt,your already dead meat...also the diesel ,with manually operated glow plugs and cold start advance switches,few thieves would probably be able to figure out how to get it to start--a built in anti-theft feature..

..my truck looks crappy enough to not attract much attention too..