Gas tank needs to move
Longer drive shaft
Suspension--if you want to keep the track bar, you'll need to move the frame mount back. This is problematic because the frame starts to slope down behind the mount. The coil mounts also need to move back and the same problems exist. So, you'll need to section the frame in order to keep the coil mounts up high. Otherwise, lose the track bar and build a custom triangulated suspension. The stock frame and axle control arm mounts are less than ideal so keeping those around will just limit you. Again, time for custom suspension. The stock sway bar mounts will no longer be inline so it's time for a rear torsion-style bar like a Currie AR. Plan on spending $3k or so on the suspension if you plan on doing all of the work and want it to be worth it.
Room for the tires--the tub will be in the way and unless you want it to look like crap, you'll want 'stretch corners' or blank corners that you can cut a wheel wheel out of. That also makes longer rocker guards a necessity so that the new wheel well positioning matches up. Good corners and rocker guards will cost you about $1k.
I'm sure there are other things I'm forgetting or haven't mentioned.
Why do you need more wheelbase when you already have 104"? Want a better departure angle?