So I got the tahoe from my dad in 2008 and it had 170k on it. It's now at 266k. I have never touched the transmission because, honestly, i never thought about it. It's been super smooth for such a long time, but now, it just feels off. I want to get under there and change the fluid. What is the best way to go about doing this? This is a 99 5.7 4l60e