I have a 91 dakota with 3.55 gears in the original 8.25 and I want to put in something higher like a 2.94 or even 2.45 what year rears can I get gears from and how hard are these to swap in? Do I need any special tools for settin up the gears?

I am not causing global warming, I am just trying to hold off a impending Ice Age!