How much wheel spin do they allow before the clutches engage? My parents work for the General and they have eaton units that grab as soon as a wheel is off the ground. I no this i a bird and it will never be a 4x4 but I've had a trailblazer (on many occasions) with only one rear wheel on dry concrete and the rest in the air. I tried buck could never get it stuck and i've had mud up bast the door jams.
I'm thinking of putting in a trac loc if it has the control of GM's eaton units
It uses a spring and clutches. It is pretty much instantaneous. They are not only good for mud bogging, you will get better take off, whether you are pulling out of a dirt driveway or launching in a straight line on dry pavement.