Background - I first heard about this rig while I was parting out a 99 Tracker.  A guy was picking things up, telling me why, and what he was using the parts on.  It sparked my interest at the time but I had four other Suzukis in my garage at that time.  I asked that he contact me when he was going to sell it.  Years later I get a call from the owner.  At the time I was wrapping up an 87 Samurai project, starting an 81 LJ80v, and wheeling a 95 4Runner.  With wife and kids, I had enough on my plate, but passed the information on to my others that would be interested.  My Dad, of all people bought the Vit.  I have only seen this rig in pictures.  The last odometer reading I have seen showed 77,XXX, miles if I remember correctly.
I say this because I'll be buying this from my Father in the near future.  He does simple maintenance like oil changes.  I typically have to encourage/help him with other things like diff, T-Case, Trans lube, tire rotations.  When it gets to in-depth stuff like ring and pinion repair/swaps, struts, trans rebuilds, he is out.

What I think I know: 
It was made/assembled in Canada (8/1999), 2.0 l inline 4 cylinder, 5sp manual, fiberglass removable top (two piece), 5 lug on 5.5" centers.

What I don't know
Badging says "AWD".  Is it AWD with selectable High / Low transfer case like you see on the FJ80 Toyota Land Cruisers, or is it selectable 2WD / 4WD high / 4WD low like you see on the Samurais?

Front outer hubs are not selectable, lock / open.  I have multiple assumptions about hubs and how hubs would relate to transfer case.  I assume the hubs are one of two types: 1. Auto Locking lending logic to the selectable 2W / 4W high / 4W low unknown, or 2. Fixed outer hub supporting AWD with selectable High / Low transfer case.

Interchangeability.  As mentioned, 1999 Tracker head lights work as replacements in the Vitara.   What years, makes, models, parts will interchange with a 1999 Vitara.

Gears and Ratios.  What are the transmission, transfer case and ring and pinion ratios?

Issues.  Everything has an issue, quirk, funny unique oddity that comes with everything.  Example: I have bought many Samurais because the Transmission / Transfer Case was "locked up".  They were not locked up.  The seat that the selector/stick was in had worn out.  A $10 fix and sold.  For the 1999 Vitara, what issues can I expect to have, can the issues be avoided, and if not, is there a fix?

Thanks,
Rob

If it's a 99 Vitara with a 2.0, it will be part time 4WD and not AWD, you will have a transfer case with 2H, 4H, N & 4L, the front freewheel mechanism is pneumatic and built in to the differential, so there are no locking hubs, just a splined lock out cap.

The Tracker headlights are NOT interchangeable, they can be fitted, but you'll need to change the grille and if you want it to look correct, the hood will also be needed.

Gears - #1 - 3.652:1; #2 - 1.947:1; #3 - 1.379:1, #4 - 1.0:1; #5 - 0.795:1 & R - 3.670:1
T/Case - High 1:1, Low 1.816:1
Ring & pinion - this should be 4.875:1, mine is, but I've heard reports of vehicles with different ratios.

Common issues - the front freewheel mechanism can be problematic, leaks, rust, damaged pump - usually not too difficult to fix, some vehicles had insufficient corrosion protection of the front suspension cross member, and this can literally rot away if the vehicle is in an area where road salt is used in winter.  Timing chains can be a problem if the vehicle is not properly maintained (missed services, incorrect oil filter.

Personally I find them to be very reliable and for the most part trouble free - I have a 98 four door, built for the South Africa market, and have no intention of parting with it any time soon.

I can't thank you enough for all the great information.  I went through the same fact finding when I got into Samurai rigs.
I wanted to make sure I was understanding this.

the front freewheel mechanism is pneumatic and built in to the differential, so there are no locking hubs, just a splined lock out cap.

If I'm understanding you correctly, during the movement of T-Case selector from 2WD to 4HI or 4Low, (I think) two things happen: 1. an electrical current engages the the pneumatic pump that in turn, engages the front differential, and 2. there is a mechanical shift inside the T-case that directs power through the front drive shaft to the front differential.  The differential sends power out the CVs to the splined lockout caps/outer front hubs.  (Assumption) The splined lockout caps/outer front hubs are free or "open" when the vehicle is not in 4X4.  If that is true (Assumption), the rotational power from the CVs engage the splined lockout caps/outer front hubs..

Close but not 100% correct.

When 4H or 4L is selected by moving the lever in the transfer case, the front output shaft hub locks the front & rear driveshafts together and closes a switch which tells the 4WD controller to engage the front freewheel mechanism.  As I mentioned earlier this mechanism is built into the front differential.  In 2H the ring gear is disconnected from the differential and when you select 4H or 4L, the mechanism engages so tha tthe ring gear can drive the differential.

The CV axles are always connected to the hubs and the differential side gears so they move whenever the vehicle is moving.

Thank you again for the information.

That is very different than what I thought.  It almost seems over engineered, but  what do I know?

Personally I think it's a crappy setup - Suzuki attempted to give the buyers the convenience they wanted, in that they did not have to get out to lock the hubs when selecting 4WD, and paid for that convenience in lost reliability.  Every automatic free wheel mechanism I have seen has had reliability issues.

1 - auto hubs that lock when the axle drives them - these have a tendency to not work if not used frequently, and even when they are working properly, they unlock when you change direction of travel - so your're going up hill in 4H, you start to back down, you're in 2H.
2 - vacuum operated free wheel hubs - loose or broken hoses, defective VSVs
3 - this crappy pneumatic "free wheel differential" - defective air pump, loose or broken hoses, leaking actuator, slipping dog clutches
4 - the Mitsubishi special ...

Mitsubishi has this vacuum operated system which disconnects one half shaft from the differential side gear - yes - when it's disconnected there is no torque delivered to either front wheel, but, the other front wheel is still being turned by the forward motion of the vehicle, and because the ring gear is not being driven all the gears in the differential are going to be turning - I don't understand how it is expected to reduce wear in the mechanism or fuel consumption, and of course, being vacuum operated, it is subject to the issues of any of the vacuum operated free wheel systems.

There are a couple of different fixes for the free wheel system - either fit a front diff from an earlier model without the air mechanism along with free wheel hubs, or disable the air mechanism by welding it engaged and fit free wheel hubs.

So I picked up on a few things

it's a crappy setup - fit a front diff from an earlier model without the air - welding it engaged