For the front I would consider a Detroit True Trac. From what people tell me you don't even know it's there when your steering. The only bad thing is if you have a tire off the ground you have to step slightly on the brake to keep it from spinning. They work great as long as both tires are on the ground.
I am currently running a Truetrac in the front and it does cause the truck to "pull/track" differently in 4wd, but it works fairly well offroad. I am upgrading to an Aussie in the front (with 30-spline Longfield Birfields and inner axles) because it is difficult to powerbrake in a 5-speed that lacks extra power. Also, limited slips are no comparison to a full locker.
If you have stock birfields, the Truetrac is a great way to go because it is much less likely that you will break things. If money isn't an issue, E-Locker or ARB are the ultimate.
