i have a 91 cherokee xj, and my automatic hubs went out i was wondering what i can do bout that. anybody know?  

auto hubs on a XJ???  

I don't meen to insult you but the jeeps havent had hub of any kind since they ended the "J" sieries & what not. unless you installed a $400+ aftermarket kit!! what youre problem most liklly is isthe vacoume lines iether on the t-case , engine or axle have come loose the selector for the front axle is on the pass. side just inside the lower control arm. the diapram may have also gone bad in that part . also check the lines around where they get close to the syspension. a line could be damaged and leaking and not alowing you your 4w.d. check on a chilton manual for youre rig @ the local auto parts store. and when you tell them the trouble your having dont be upset if they try to sell you a "vacume kit" there about $30 to $50 bucks . its a good Idea to have that kit it will make it sooooo! much easier to find that and many other problems also you wont ned to con a friend into helping you to bleed brakes ever agian(if you dont have the kit you will understand once you do and read through the bookleet of thing  that you can do w/ the kit)

 but in all honesty and I'm sure most of the guys in this fourm will agree w/ me in saying the best thing you can do is junk that axle and get a NON selectable front axle out of a slightly newer jeep like post 93!

i have the 4x4 Posi-Lo which is a driver operated manual cable system that replaces the failure prone vacuum engagement system, and its locking up because i have taking my diff case off and locked it in and everything is locked and moves but when i unlock it it dont move so i know it aint no vaccum lines

Save your pop cans, Sell your crummy 30 front end to some one else and have a 44 front axel built for your rig. You will be much happier in the long run.  

Pick up a Rubi axle if you need a d44, one draw back is that it is a low-pinion.  Or you could get a set of d30 TJ shafts with 760 u-joints, a great improvement over the 260 u-joints found in the vd set-up. The TJ shafts will drop right into your XJ d30 though you will need a long side inner seal, and you will still have a high-pinion axle. If you go with the TJ shafts you could go with the geaseable seals from Alloy or Superior and possibly eliminate the inner long side seal next to the carrier.