I've got a 1999 Dodge 1500 4X4 and bought it last year and finally working on the last kink-There are two vacuum lines that go to the CAD(I think I've heard someone call it, and the one on the left as your looking at it from the rear of the axle goes to the floor actuator or somethin-that ones not the problem-the right one has a good rip in the old hose-question is, what exactly does that one do because I followed the line and it just runs up through the fender well and caps off to this little plastic piece-My 4X4 engages and everything but once I start stepping on the gas I can feel a knock in the front right and it is definitely not supposed to be like that-so I was wondering if it could be that hose but then again it looks like its capped off and is non functional....Any advice or wisdom would be greatly appreciated

 

here you go. both of the little vac lines on the cad should return to the switch on the t-case.
vac on one line should shift the fork in the cad and connect the axle.
vac on the other should shift the fork back and disconnect it.

there is a bigger, fatter hose coming off the front axle that goes straight up to the inner fender, and has a loose looking/feeling cap on the end. that's the axle vent.

http://www.4x4wire.com/dodge/tech/solid_axle_cad/
http://www.dodgeram.org/tech/repair/..._engagment.htm

 

sound to me like your missing a vacuum hose. As for the bigger vent tube, that should be repaired because it is their to prevent water from entering the front end. You could go with a posi-lok, but they are 200 dollars.

 

Not to throw you for a loop, but you say it engauges right? That clunk might be a bad u-joint.. Just wanted to throw that out there becuase if it works that might not be a problem. But then I again everybody is wrong sometime.

 

Yeah someone told me that I could have some bad u-joints but I wanted to make sure that the vacuum lines were good before going further into the darkness(as to speak) and spend a ton of money-I'll have to take another good inspection today and see if there is that big hose and the smaller hose-but I know now that the vent hose has to be replaced-Thanks guys, I'll keep you updated