It's really an expected miles vs. cost decision you have to make. Obviously, all else being equal, a well maintained '08 with 120,000 miles has more life left in it than the same well-maintained 04 at 250,000 miles. But, you pay for those extra expected miles. If you can afford the extra money, you're probably better off going newer, but if not, the older vehicle can still give you a lot of solid miles.
Given that, the older vehicle only really makes sense if you can do a lot of your own maintenance. The major drive train components (engine, transmission, diffs, etc.) have a lot of life left in them, assuming good maintenance. If the frame is relatively rust free, your major maintenance concerns are stuff like O2 sensors, accessories (alternator, PS pump, etc.), wheel bearings, light bulbs, various hoses, etc. None of that is terribly hard to fix in your garage, but the money really adds up if you have to have it done by a shop or dealer.
Fortunately, websites like this make maintenance info readily accessible, even for fairly complicated projects, and Harbor Freight brings the cost of good but not great tools down to where you can afford them.
Bottom line is, if $7-8K is what you have to spend, and the off-road mods are of interest to you, the vehicle you're looking at looks to me like a strong contender.