So, I am acctually strongly considering an SAS for my X. I have a friend whose dad welds, but this isn't the point. A couple questions follow.
With the SAS, you don't have to have a body lift to correctly install it do you?
When you've got the D44, which i have found and is driver side drop/non-vaccum, you don't necessarialy have to install lockers right away do you?
And for those who have sas'd what kind of time frame did it take you?

thanks guys in advance

No body lift needed, front locker is optional but you may save some time and $ setup wise since you're going to most likely need new front gears to match the rears anyway. Might as well locked it while the gears are getting done if your going the professional route. If you want a full time locker...Aussie's are ~ $250 otherwise save up for a selectable like a ARB or Eaton E-locker. If you don't have a rear locker get one of those 1st.

Did mine over a weekend.

With a few hands at a mod day or something it could be done in a day if the axle is ready to go, brackets welded on, etc.

not to sound like a total idiot, but what are the original gears in the rear?

WooHoo MOD day! We have some good SAS experience in the club.

4.65 for a 2000 Nissan H233B. Best match would be 4.56's for the D44. I ran that setup in my SAS Pathy and it was ok. Little bit undergeared but managable for <=33" tires. Anything bigger go to 5.14's or 4.9 which you can find in the 2002+ at the junk yard or something.

I'm running 35s right now on the independent front suspension...doing an SAS end of next month. I'm not going for the front locker immediately either...short on funds after all is said and done. I'm keeping the 35s and going with 4.88s in the front to match, as close as possible, the stock 4.90s in the rear H233B. So, if you're thinking about stepping up to a 35" tire, then at least get 4.88s for the front, or whatever is closest to your rear axle ratio. So to answer your question, no, a front locker is not "necessary" to do an SAS, but as XToolbox pointed out, if you've got the cash and you have to regear the D44, then you might as well go for one. I have an ARB Locker in the rear, so I'm not in too much of a hurry personally. I'll probably end up going with an OX locker for the front when the time comes...always wanted to try one out and I hear good things about them. Good luck with the SAS if you decide to do it...

If you're staying open diff in the front you'll need to buy a new carrier that will fit 3.92 and up gears... the stock carrier won't work.

They're cheap, though... $60 from completeoffroad.com. It doesn't come with the guts (spider gears etc) but you can use the ones from the stock carrier.