If you are seriously interested in the SL follow my sig link to the superlift write up I did in there. Read it so you know what to expect.
As for the front shaft I don't care what kit you run if you drop that front diff 3 or 4 inches you better get the shaft lengthened and a new joint put on the t-case end or your asking for it. I got both shafts lengthened and the front one with a new flange for $400. Be prepared to spend more than just the cost of the kit.
The front shaft has a realy crapy CV style flange at the t-case end. Much more angle than factory and it will bind. You could be ok and but a u-joint or you could bust a pinion, or the entire diff housign ($$$). SO cought it up and get one made.
I am not knocking this kit, it has been well for me and has held up well, just be prepared to do it right.