OK, I will explain, or at least try to....
In the older Deuce and five tons, they used a "sprag" type of transfer case which engaged the front axle if slippage was occuring. Otherwise the front axle was free to operate slightly out of snyc with the rest of the truck which is necessary for ease in steering and avoiding driveline binding.
There are inherent problems with the design and it is something that needs to be kept in adjustment and monitored. Serious damage can occur if the truck is allowed to slide backwards while the rears are in forward motion and vice a versa as to reverse.
On the deuce, they changed the sysytem of engagement so that an air actuator engages the front axle, and only upon driver request via an air switch in the cab. This is very much the same as your contemporary 4WD with the shift on the floor for 4X4.
Sprag equipped trucks generally cannot be equipped with lock out hubs like an air shift equipped truck can.
The military made the upgrade to reduce maintanence and problems with the sprag design and most of the deuces that have or are coming out now are air shift equipped. Occasionally, and I say OCCASIONALLY, a Sprag transfer case 2-1/2 ton truck comes out of the military, or government service and is available for auction. Not being an expert on the five tons, I will state that most of the 5 tons have a sprag type of system.
On the whole, almost everyone would tell you they prefer the air shift for absolutely trouble free operation.
While it is possible to upgrade a Sprag truck to an air shift transfer case. It is heavy work, dealing with very heavy and unbalanced weights of the transfer case, and then you have to add the air shift switch and indicator wiring along with the necessary air plumbing.
Don't be afraid to ask questions but do expect many to encourage you to use the search feature because if you do, you will end up learning all sorts of stuff you would not otherwise be exposed to. Part of the hobby is learning and spending time solving your problems in the form of the questions you have.
My advice in using the search is to be as simple as possible in your search terms and that will return you the most results that are linked to your search string. You can always search again and add more to limit the results, but always start basic or general in content.
I do hope this helps, and enjoy the hobby, or addiction depending on how it affects you.
RL
