Hmmmm..............., thanks for the explanation; I have to say that in my millions of miles of very heavy-hauling, I have never had reason to resort to such tricks to get rolling.
Usually, my problem in such situations was always how to keep from sliding, whether the wheels were under power or no.
With a diesel, I never have trouble coming off the clutch and getting underway; now, a spluttering gas-burner, looking to die at the least excuse, is often a different story.
In my experiences and observations, an automatic in such a situation won't launch the truck from it's tracks, just sit there and moan.
Got to remember, we are talking for extreme conditions here. That parking brake can also help when you are on such an angle that one side is unloaded or other conditions that would cause one wheel to not want to grab as well in that it allows your posi to get all hands on deck as you are pulling out.
Of course with an autobox you can do the same thing by simply riding the foot brake a little
I used to run my jeep pickup put in the mountains and deserts of CA and wrenched at a Jeep dealer and did my fair share if messing around in places I shouldn't.( and a lot of repairing the aftermath of those who weren't so lucky)
Those laws in CA have been in place for a long time, I slid and nailed the whole steering gear on a rock the size of a VW one time and was facing a bill for a helicopter recovery because it was way too far in for any other kind, and I got this bright idea to use my snow chains to replace the steering linkages. Wrapped them around the ends and went for it. Had 2.5 turns of free play in the wheel and my buddy was moving rocks out from in front of the tires to keep them from kicking me over a cliff but half a day later, we got out of the canyon, and instead of calling for the wrecker from there, we just kept on driving and made it home
