Well, this is my York air setup.  I have to say this is one of my favorite modifications that I have done on the XJ.  The more I went off road the more I hated looking for air to air back up my tires.  Not to mention how aggravating it is waiting on those cheap little cigarette lighter powered compressors.  So I started doing a lot of research on the AC compressor to air compressor swap.  Soon I found out that the best option for this is the York, because of its oil sump built into the unit.  Not to mention the amount of air these thing can pump.  So in the back of my mind I kept a look out for a York.  To be honest I really did not think I would find one and was real uncertain if it would even work in an XJ.  But again at my local Jeep Dealer I was looking around and I see a York setting on a work bench.  I am like hey is that a York, and what are you going to do with it.  He just smiled at me and said "Oh I found that at a junk yard when looking for parts for my J20".  So I haggled with him and took it home. SO a few weeks go by and I am just trying to find a place for the thing to even fit under the hood.  Well, the only place it would fit under the hood was where I had removed the stock air box to install a K&N air filter.   Originally I was going to put a second battery there, but I threw that out the window when I realized there was a good chance of putting a York there.  Ok so I found someplace where it would fit, now on to the next step getting it power.
    It took a few weeks of searching from time to time in the junk yards looking for a pulley that I could bolt onto my Harmonic Balancer that would not stick out to far from the engine.  I got this idea from looking back at the CJs and the way AMC added air-conditioning to the CJ.  They added a pulley onto the Harmonic balancer and then ran it to a York for crying out loud.  So I wanted to use the pulley AMC used on the CJ, but AMC decided to stamp all those pulleys on so they are not removable.  So the search continued.  I finally found a pulley off of a Ford V8 in a scrap yard that I could use and bolted it onto the Harmonic balancer.  So now we come to the mount for the York.
    The mount for my York is complex and I am sorry I don't have a pic of it.  It consists of 1 1/2" tubing that is welded to a piece of flat plate on one end so I could bolt it to the threaded holes on the engine block just in front of the motor mount.  The tubing then bends up towards the opening I made where the stock air box used to be.  I then crossed braced the tubing with angle iron off of a bolting place on the air intake manifold.  So then the mount twist up toward the front of the engine compartment and then is welded to the plate mount that the York can then bolt to.  The mounting plate has slotted holes in it so the York can move to get tension on the drive belt.  Ok, the mount at this point has just a little bit of play in the mount when the engine would shimmy, so I welded one more piece of angle iron off of it to the back of the power steering pump mount.  The next step was finding a belt.

    The belt I ended up using was a Napa belt that is 57 5/8" long and 3/8" wide.  So, I have the York in and the belt on giving it power.  All that is left is connecting it to a tank right?  Hehe I wish it was that easy.  Now I had to find a pressure switch, check valve, regulator, safety release valve, pressure gauge, drain cocks, plumbing Ts, air lines, power switch, and air tanks.  Well, I got the pressure switch, safety release valve and the check valve from Grainger.  The power switch I attained from Radio Shack.  The regulator, plumbing Ts, drain cocks, and pressure gauge from Lowes .  For the air lines I used 3/8" I.D. hydraulic hoses with crimped ends I had made at Napa.  For those of you who think the air lines are a bit extreme you have to remember how hot it gets under the hood and how hot the air is coming out of the York.
    To see how all this stuff goes together look at my schematic.  Please don't laugh to hard at my drawing skills on this thing, but I think it will give you an idea as to how I hooked it all up.   Now for my air tanks I made air tank bumpers to hold the air.