Brake Booster

I need to replace the booster in my XJ. I have been looking online to get feel for what is out there. I see prices ranging from about $100.00 to over $250.00. Why such a large difference in price? I think I may go to the local Pick-A-Part and grab one. What years should I look for. I know the early XJ's with the single diaphragm (that was on my 1994 XJ) should be avoided. Just from memory, it look like the ZJ, WJ and Explorer uses the same booster. Which would be the best fit for my (1996) XJ?

When I got my current XJ ('91} my brake booster was shot. I got a used one (with a warranty) from a local JY for $35 and it came with a master cylinder (so I now have a spare). If any of your yards don't have one, you can look here:

www.car-parts.com

It's a large, searchable database of JY's from all over. As far as years that work better, I am unsure. Someone more knowledgeable will chime in, I'm sure.

I would trust a "it worked when it was parked" junkyard part over anything from A1 Cardone.

I am back at the brakes again. have not driven the XJ since October. My DD is a 1993 Toyota pickup so the XJ is my toy.

I removed the booster yesterday and took a good look at it. It appear as if it is not user serviceable. I wish it was. The price of a remanufactured one at the auto parts places here in Jacksonville, FL is over $80. About the same price as Summit Racing and other online stores. From the local Pick-Your-Part is $25 +/- and an $8.00 core. There are plenty of ZJ, WJ and Explorers at the yards and to the untrained eye ( booster installed) they all look the same. Would one from a WJ work with no modifications?

Looking back at the booster I just removed, it is not obvious as to what caused the hard pedal. I would however point my finger at the atmospheric inlet valve assembly. According to my workshop manual, there should be a filter there ( where the rod from the pedal go into the booster). On my XJ, it have completely disintegrated and probably got sucked into the rear diaphragm housing. The manual also said it depended upon the difference between atmospheric pressure and vacuum to operate properly. This booster have no leaks as far as I can tell It is just hard to push almost as if the booster is not working.