The red arrow points to our intended hole we need to drill, this is the larger of the two bits you will need.  Triple check there are no wires on either side you can chew up and let the chips fall where they may.

This is the vacuum hub and is your enemy.  You must terminate this part with extreme prejudice.  I've always wanted to say that. On many older 4X's this will leak either at the line or the internal diaphragm, if you are even thinking of replacing this part the choice is clear Posi Lok.

It's hard to imagine that this small amount of loose parts will come together and make life so easy.  The folks at Posi Lok include everything you will need to do this conversion, I found myself needing nothing from the hellbox to supplement Posi Lok's parts list.

Posi Lok tells you in their instruction guide that you will need two drill bits or a uni-bit.  I had both but the uni-bit makes child's play out of drilling through the tub of the Jeep.  Notice the red mark around one of the steps on the bit, this make for an easy reference while drilling under the dash in the dark confines of the Jeep, try it, you'll like it.

I said you will need a flat head screwdriver, in order to get the head through the inside mounting bracket of the Jeep you need to unscrew the T-Handle.  The bracket is powder coated so it will need a little persuasion to push it through, resist the temptation to smack it with anything you could damage the mechanism or chip the powdercoat.

The mount is ready to receive the cable.  We have already drilled the hole in the firewall.

The aforementioned hole.

A view from the engine bay.  This hole will eventually be filled with black silicone to keep water out.

Ok, the interior is done.  I know somewhat anti-climactic huh?  I told you this was easy.

Our Jeep has a 7" lift on it with 35" tires so we had plenty of room to maneuver.  4 bolts hold the cover on, so go ahead and remove them.  Place the oil catch underneath so anything that spills out doesn't offend the ground. Depending on how long the modulator has been on the vehicle will depend on how much coaxing it will take to remove it.  I had to threaten it's family, that didn't work so I used a rubber mallet.

Once you have the cover off this is the view.  The sliding coupler is what is actuated when you ask for the hubs to engage.  Not a lot to ask for but after a while vacuum isn't enough.  If there are no major problems nothing will fall out except a little bit of gear oil, not enough to have to refill.

Here is the most difficult part of the installation.  The arrow points to a circlip that borders the fork, there is one on the other side as well and both of these must be removed.  Once you have accomplished that you can slide the pin out that holds the fork in place.  It is worth noting that now would be a good time to inspect the fork for any wear, this usually occurs where the pin rides and will manifest itself in the form of an oblong hole causing the fork to wobble which in turn can cause the fork to not be able to engage the hubs properly.  Our fork had absolutely no wear leading us to believe the hubs were engaged rather infrequently.

Before you install the fork into the new cover provided by Posi Lok look at the next picture to see the orientation of the fork...

...the fork must offset to the left as you are looking at the axle in order for the slider to engage and work properly.  (the arrow points tot he other circlip)

If you have finished this job before you finish the beer this is what it will look like.

Our Jeep has other issues we have to resolve before wiring the hub selector light for the dash (ours doesn't have one that we know of) So we didn't connect the wires, if all the parts are on your Jeep it will be a simple matter of splicing into the already existing line.  The Posi Lok folks even included the wire and connectors for you.

And for those who want another sticker for the dash, Posi Lok includes that also.

All in all I would have to say I am very impressed with the quality and ease of installation.  The only point in the supplied directions that gets a bit fuzzy is which way the fork aligns after you remove it from the stock piece.  I admit I installed it incorrectly the first time and had pull it apart and redo it.  No biggy.  It only took an additional 5 minutes to get it right.