The single best improvement I can suggest for a Disco II is to ditch the stock Goodyear Wrangler tires for quality rubber like the BFG AT/KO. It is a night/day improvement over how the Disco rides and sounds.
If I could redo the purchase of our '03 I would definitely get the '04 with locking center diff. I am finding them with 60K miles in the $10K range locally. The '04 is arguably the best Disco from LR...like the '89 911 was the best from Porsche...
