This is a very common question and also a very good one.

The Discovery series one (DI) ran from 1989-1999, US models from 1994-1999.
Pre-1996 models have the 3.9L V8 with a distributor, all models after that have the 4.0L engine and electronic ignition.
There are thee trim levels and all had the 7 passenger option.
Common DI problems are as follows.
Sunroofs not working due to bad tracks.
Power windows not working due to a bad window regulator, easy fix.
Rear windows not working due to a cracked window lift ECU, easy fix.
Power door lock actuators not working, easy fix.
ABS light staying on, could be a bad wheel speed sensor or a bad ABS modulator. Could be expensive or free to fix.
Center Differential Lock (CDL) lever being seized due to lack of use.
Cargo door not opening from the out side, pop the LR emblem off and lube it with silicone spray.

The Discovery series II (DII) ran from 1999.5-2004.
The 2003 and 2004 model years have the 4.6L V8.
1999.5-early 2001 have the CDL as well as the 2004.
The DII also came in three trim levels and all had the 7 passenger option.
The 2003 has potential oil pump problems and the only fix is a new engine.
Common DII problems are as follows.
Power windows not working due to bad window regulators, easy fix.
Power door locks not working due to bad lock actuators, easy fix.
The cranks shaft sensor (CKS) going bad.
The throttle body heater plate leaking, easy fix.
Head gaskets going bad, change your coolant every 2 years and you can help avoid this.
The front driveshaft MUST be rebuilt using greasable u-joints, if you dont you WILL be buying a new transmission. ($7,000)
The "3 amigos", that is the Hill Decent Control (HDC), ABS and Traction Control (TC) lights all being on at the same time.
The Self Leveling Suspension (SLS) going flat.
The Secondary Air Injection (SAI) pump can be noisy, clean the air filter to it every 6 months.
The Active Cornering Enhancement (ACE) is very reliable and a good option.

All model years require premium gas, you can expect 12-14 MPG in the city and 16-18 MPG on the expressway.
www.roverlandparts.com is a good used parts supplier.
www.atlanticbritish.com is a great new parts supplier.
Go to AtlanticBritish and find the "tech tips" page and read up on them, print the pages that pertain to you, like "how to reset the HVAC from C* to F*"

Do your research.
www.edmunds.com
www.NADA.com
www.KBB.com
Test drive many, dont buy the first one that you come across.

 

Just a small correction to otherwise a good post spikey,

the series 2 Disco came out in 1998

























and you forgot to say buy a Diesel!!! :P

 

LOL!!
But the DII didnt come to the US until 1999.5, and there you go again rubbing in that we cant get the 28 mpg diesel here in the US.

 

How can you get the Center diff lock lever unseized?

 

Depends on how bad it is, I used lots of penatrant/lube and sprayed the hell out of it and worked it alittle every day.
Liquid Wrench is what I used.
Crawl under the truck while a friend wiggles the shifter so that you can see what needs lubing.
Spray it with carb cleaner first, work it and let it dry, then use the pen/lube, wiggle it.
Do this until it starts to work or a week of trying everyday.
If it wont work after a week then you need another aproach which is alot more work.

 

Thanks. Everyone here is really helpful.

 

I own a 04 Disco, what does greasable u-joints have to do with the tranny? Maybe binding in the front end? The transfer case does not have a vicous coupler? Please answer....Thanks.

 

When the u-joints fail from lack of lube the driveshaft will drop at 60 mph and shred your transmission before you can blink.

 

What they are warning you of is a failure of one of the u-joints in the double cardon joint. Crawl under your truck and look at the front drive shaft. The BIG round piece is the double cardon joint. When it fails it is usually at highway speeds and the drive shaft is spinning at something like 2500 RPM and that shaft knocks a huge hole in the side of your transmision. I got lucky and was very aware of the problem, so I got mine fixed and found several broken needle bearings in the centering ball, but the ujoints were fine. All has been replaced so I am good to go!

 

ohh ok, I was thinking you guys were a little crazy! I understand the potential hazard. Thanks. You can usually hear a double cardon about to fail. It will squeak and squeak.