If you have CAD the front hubs are constantly mechanically locked and the disconnect is moved to the middle of the axle tube instead of out at the hubs. The CAD system and auto hubs are a convenience. Different people like different things so they come up with different ways to accomplish the same job. I don't like to have to exit the cab, as I would have to do with manual hubs, every time I use 4x4 so I like the CAD system. Convenience can have its draw backs because it makes things a little more complicated most of the time if you have to work on things. But I still prefer the convenience.

Some people like chocolate ice cream and others like vanilla. This is why they don't make only one flavor and remove all the hocus pocus. Wouldn't it be a dull world if they only made one kind of everything we use.

If you have specific questions state them and we will try to answer them all until your confusion is cleared up. That is why we are all here.

Im a butter pecan kinda guy myself.
To the OP:
Assuming you have a central axle disconnect, (CAD) than your description of how it works is basically correct. Transfer Case sends power forward to your differential, but you are only in four wheel drive if your CAD is actuated. Sort of like unlocking one hub on a manual hub truck. Just because you have one hub still locked in, doesnt mean you are in three wheel drive. So yes, you are correct. I would bet a handfull of marbles that your CAD or the vacuum lines going to it need some attention. Can you post a picture of your axle for us, sort of center left?

Maybe this will make it easier, being as we would have the same setup if you have a CAD. This picture is taken from under the drivers side floorboard facing towards the front of the truck. Note the leaf spring u-bolts just to the left of the CAD. If you see something like this under your truck, then there is a good chance that is your problem. Mine doesnt look like this anymore being as I have modified it, but that is it in its stock form. Hope this helps. Also, side question: How do you post more than one picture on here? It keeps telling me that I have dont have enough space for another.

Eric, use photobucket and upload your pictures to it then use the links here. Much better than using the attachment thing here

I am not the OP but it kind of sounds like your talking to me, I have had my truck stuck in snow before and I know when i am in 4x4 only 1 front tire spins, I always assumed that was because there is no posi in the front axle. am i wrong?

Seal I agree with you on the hubs I really like this setup and dunno why anyone would want to get out and lock or unlock hubs. My question is why the front end either needs a vacuum system or manual locks on the hubs at all. is it for cornering? I suppose what I'm wondering is why not just have it set up so if the transfer case is shifted into 4x4 then it starts spinning the front driveshaft and your in 4x4 mode shift out it stops spinning it and you are back in 2wd.

beakerztoyz: You are correct about only one tire spinning due to no posi. Some front diffs don't use the vacuum system, manual hubs, or auto hubs. They are locked all the time as far as the diff goes. These systems are not used on most trucks because of the increased drag and excessive parts wear.

Thanks for the explanation Seal

Gotcha. Thanks for that.

can anyone point me in the direction of the 4x4 posilok device (cable actuated vacuum motor replacement)? everywhere i looked is sold out

Did you check Summit?