I love my front locker. So far its holding up just fine. I romped on it pretty good at the Midland meet. I had the front end bouncing up and down trying to get up a really steep hill and it held up. I was pretty worried I was gonna snap a CV doing it, but it didn't break.
The only place you can get the aussie locker is from aussie lockers website, mine was like $250 shipped. http://www.aussielocker.com/
I'd strongly advise against welding the rear. You might not think its that bad, but you'll hate if you have to drive with it like that all the time.