It is a 5.9 BTW.
It MIGHT have tranny issues, mine didn't at 143k miles. If it has gone that many miles, it has either been replaced at one time, or it is going to need to be rebuilt.
Cold a/c-probably just needs to be recharged.
Seeping from the front axles can easily be fixed, there is a seal inside the axle housing that you have to pull out and replace, it is like $16/each side for the seal(it has been awhile, so don't quote me on that price), and you can do it yourself, but it will take some time.
Rear brakes shouldn't be a problem to fix because they are drum brakes, mine went out on me going down the road, as the cylinder inside there was leaking. Not fun, and had to be at a dealership over a weekend.
Honestly, I got 3K on my 97 3 years ago when I traded it in, with 143k miles. Nothing major was wrong with it, except for it needed new exhaust(and that set off a check engine light, which lowered the trade in price from 4 to 3k). Everything else that had gone wrong had been replaced. I wouldn't pay no more than 5k for one with 170k miles, IMHO.