ok i have a 97 dodge ram1500 v8 so today i had a chance to look in to it and see whats the problem i took the rear drive shaft off to see if the 4 wheel is working.. so the front drive shaft runs when you put it in 4 wheel drive but the car wont move... any idea wats going on please

 

Check the vacuum lines going to the CAD on the axle.

 

you mean the one the the plug withblack and white and it goes to the transfer case

 

here's how it all works.
http://www.dodgeram.org/tech/repair/..._engagment.htm
http://www.4x4wire.com/dodge/tech/solid_axle_cad/

you don't have to remove drive shaft, just put it up on 4 jack stands.
our trucks have a split axle on the passenger side.
your CAD is not engaging the connecting collar.
without it, your front drive shaft just spins all the power through the spider gears to the disconnected passenger half.

CAD is fairly simple. vacuum switch on t-case. vac diaphram and mechanical slide inside CAD. note the 2 vac lines at the cad. you should have vac on one in 2wd and vac on the other in 4wd. if you do, then the problem is in the cad. if you don't, the problem is at the t-case or the lines themselves.

 

Install a posi-lock unit and never worry about the vacume lines again.I ordered mine from summit racing and have had no problems and it is easy to install.