4x4 questions

[Low87]

So my experience with 4x4s spans all of about 4 hours total.  Bought my first one Sunday night.  I'm realizing in reading through the threads here how little I know.  I'll keep going through the forum, but is there also a good place to learn the basics?  I don't plan on mudding, rock crawling, etc., just building a reliable truck that can run 4x4 when needed. 
Mine is an 89 GMC Jimmy.  I'm seeing 205 vs 208, which I assume is the transfer case.  How do I tell what I've got?  I'm going to go ahead and service everything (fluid changes, check seals, etc) so any advice on the 4x4 equipment would be great.

[VileZambonie]

89 probably has an NP208 or NP241. Go underneath and look at the tag on the transfer case to see what it says.

[Captkaos]

Should have a 241 in it.

[Blazin]

Whats your motor, trans combo? As far as axles it should have 10 bolts if its unmolested.
Some Chain and Cable lube on the 4x4 shifter rod pivot points underneath is always a good idea.
Check out the front axle joints. Reach in and see if they have play, or are sloppy, or froze up? Like you would a U joint in a drive shaft. Jack the wheel up, lock the hub and rotate the wheel. You should be able to see if the cross is lose in the caps. Also if you rotate the wheel and it tries to turn the steering wheel, or steer the tires out of your hand they may be froze up.