Good news. IIRC, there is a pin that AC shaves a small amount of material from, that's it. Don't quote me on that though.
There's a guy on the AC board with a Pathfinder that simply fused his front diff together rather than shell out the $ for a front locker. I've heard of doing this in the rear and I wouldn't even consider it, but ya know, for the front it doesn't sound too bad!
With free-running hubs, there is absolutely no difference on the street since the wheels can still rotate indepedantly in turns when unlocked. Of course, once you're in 4WD, you're always locked. The only drawback I know of there is that there is always the chance of increased stress on the axles even when you woudn't otherwise need the extra traction, but it shouldn't be much more risk than an auto-locker that can kick in at any time and load the axles the same anyway.
Yes, I know it isn't the best solution, but it seems to me a cheap way without much risk. Anyone else want to chime in, feel free.
Brent