I have a 2009 with a solid rear window, I have a chance to pick up a slider but it's from a 98. They look the same but just wanna check if it will fit and how much of a pain it is to swap out if they do fit.

 

You should be OK, 1998 to 2010 show same rear window size

I would see what local auto glass shop would charge to do the swap, your good non-sliding rear window may also be worth something to them, maybe not but hey $20 off is $20 off, lol.

1998 and up rear windows were glued in using urethane adhesive because of previous years "leaking" issues.
So can be hard to take out and you could scratch the paint while trying to do it.
So grain of salt

But yes you can DIY it, there is a tool called a Windshield Stick which is not expensive, and will make it easier