The Dana 30 washer fix is easy to do. I've did it on my YJ when the back of the fork broke off.
There is a write up, but i can't be bothered to google it right now (it might be on Junior Users).
OK, pull the vacumm motor (the assembly on the back of the axle), leave the hoses and wires connected. Before doing anything else, start the engine (trans in neutral!), and engage 4wd (Hi or Lo, doesn't matter), see if the fork slides back and forward. If it doesn't, you've got no vacumm. Up to you to troubleshoot that problem!
As far as the washer fix, NOW pull off the wires and hoses. Go to the bench and pull the 3 clips on the fork shaft (2 small, 1 large). Just inboard of the diaphram housing (The big round bit), is a place to unscrew and remove the shaft. Now you need to find about 10 washers that fit over the shaft, but also fit inside the housing. Can't remember what size i got for mine. Take the whole thing to Home Depot hardware aisle if needed.
Now you've got the washers, hold the housing V pointing to the floor. Start to slide the shaft back in. As you slide it in add washers until you have the shaft almost all the way back, but just enough room to fit the fork back in. It should take about 10 or 11 washers IIRC. When the fork is held snugly on the shaft by the washers, tighten the shaft back up.
Slide the big ring that joins the axle shafts in the axle together to the middle of the axle, ie towards the diff. Now replace the whole assembly, making sure the selector fork goes around the ring. Bolt it all back up, re-attach everything (even if the hoses didn't work, at least you don't have to figure out what to do with them!) and you're done.
You didn't say if you have a front locker. If you do, you'll be staying in 2wd whilst on tarmac, or getting a big surprise!