Everyone has told you, but yes, this is a screaming deal, especially if you want to go to 4.10's.
If you look in my build thread below, I bought 2005 Rubicon Dana 44's with 4.88's, got them for $4k and then sold my 30/35 for $2k or a touch more actually. The front had an auto locker, so got $1,200. Don't forget you can get some for your currents.
$1,400 I would purchase and pay shipping to Texas right now, and sell for $4k and people would be lined up to pay it.
The air lockers are there to inflate the bladder and engage the lockers in the stock Rubicon lockers. They came bolted to the skid by the output of the Transfer Case. I put mine under the hood, pics in thread, and they were like new. Even if he doesn't have them, you can get others, but you'll need to be careful, you need to have the right 5psi pump, or a regulator, but all doable, just simple wiring for switches and air lines, fuel line actually what I used.
This is not a hard job to do either. I say that, but there could be some issues as every project, but again just work, like I had to work on bending the rear hard brake line etc. No biggie.
https://wranglertjforum.com/threads/2005-texas-jeep-tj-never-sell-build.37076/